Suggest you change to Ublock Origin instead of Adblock Plus. Ghostery works also (can run both at same time)

It is possible that the issue is your New Tab Homepage. https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems?redirectlocale=en-US&redirectslug=Troubleshooting+extensions+and+themes

I gather you have been downloading the Full Version Installers. https://www.mozilla.org/firefox/all/ If not Uninstall and reinstall with the above.

Note : Win 10 can and will change replace your drivers with Microsoft's. https://www.howtogeek.com/302595/how-to-stop-windows-10-from-automatically-updating-hardware-drivers/ Can check in the Device Manager.

Suggest also Update all Drivers including your Video Card.

If you think it could be your Win10 OS Can do this : (also copy/paste/save for future fixes)

Repair System Registry and Files

(FOR DOING Above & Below - WINDOWS All OTHER VERSIONS - Use Search To Find Command Prompt ** Enter CMD.exe to Find COMMAND PROMPT Then Right Click & RUN AS ADMIN)

To run the SFC command use the Windows key + X keyboard shortcut to open the Power User menu and select Command Prompt (Admin). Type "SFC /SCANNOW" (without quotes or copy/paste) and press Enter. For more information on using SFC, please refer to the Microsoft KB: Use the System File Checker tool to repair missing or corrupted system files

Run the Windows Deployment Image Servicing and Management (DISM) and System File Checker (SFC) tools as Administrator. The DISM and SFC tools scan the integrity of the Windows image and all protected system files replaces corrupted, damaged and incorrect versions. (FOR DOING Above & Below - WINDOWS All OTHER VERSIONS - Use Search To Find Command Prompt ** Enter CMD.exe to Find COMMAND PROMPT Then Right Click & RUN AS ADMIN)

Windows 10 To run the DISM command use the Windows key + X keyboard shortcut to open the Power User menu, then select Command Prompt (Admin). Type "DISM /Online /Cleanup-Image /RestoreHealth" (without quotes or copy/paste) and press Enter. While running DISM you may notice the process will appear to pause at 20%. After a few minutes the operation will continue.

Note : SFC fixes files locally using files found on your system. Note : DISM goes up to Microsoft for new ones.

Note : Firefox 56.0.2 is current release https://www.mozilla.org/firefox/all/ Full Version Installer Note : Firefox 57 Quantum release date Nov 14th https://www.mozilla.org/en-US/firefox/quantum/ Note : Legacy Extensions will be disabled and or removed.

Please let us know if this solved your issue or if need further assistance.

This can happen when all location/address bar suggestions have been disabled.

The location bar drop-down list can show history items, bookmarked pages, pages opened in tabs, and search suggestions. You can set what suggestions show when you enter an URL in the location/address bar bar via Options/Preferences -> Privacy & Security

• Address Bar: When using the location bar, suggest:
  History
  Bookmarks
  Open tabs

You can check for problems with the places.sqlite database (bookmarks and history) in the Firefox profile folder.

• use "Verify Integrity" on the "Help -> Troubleshooting Information" (about:support) page
• https://addons.mozilla.org/firefox/addon/places-maintenance/

See also:

• http://kb.mozillazine.org/Locked_or_damaged_places.sqlite
• https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

If "Verify Integrity" on the "Help -> Troubleshooting Information" (about:support) page or Places Maintenance can't repair the places.sqlite database then remove all places.sqlite file(s) in the Firefox profile folder to make Firefox rebuild the places.sqlite database from the most recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created
• http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Wow! That would have to be one of the most comprehensive support responses I've ever seen. Many thanks.

I won't respond to all of your suggestions, I'll just say this....

This problem started about 48 hours ago. I've been dual booting Windows 7/10 for 7 months and there have been no problems. I've been using the same add-ons for all of that time. Indeed, the problems persist in safe mode with add-ons disabled.

It was only when I upgraded to v55 that Firefox started telling me that Adblock was "Legacy" and I should upgrade it. I did that and found that ads were no longer being blocked.

My WIndows 10 was created using MSMG toolkit from a Creators Update ESD file. I have removed all Microsoft bloatware, Defender, Cortana and so on. I have tweaked much of the privacy and security settings using group policy and registry changes. I'm quite familiar with these tools. Including SFC, DISM and other administrative tools. Again, no issues over the last 7 months.

There have been no problems at all.

I have also tweaked some settings using about:config (Such as disabling auto play, moving the cache folder off my C:\ drive and such). Again, there have been no issues with this.

Driver updates from Windows are blocked. Well and truly :) All driver updates are controlled by me, as they should be. If only I could say the same for Windows updates :(

My Graphics driver is 382.53, which is not the latest, but is required as later drivers have issues with several games (Such as Doom), But I'm on top of those sorts of issues.

Two days ago in frustration with ads not being blocked I reverted to v54 and that's when problems started.....

A note re the dual booting: Both Windows 7 and 10 do NOT share the same cache or profile folders. I have kept them separate to ensure no conflicts.... Not really relevant, but for completeness I mention it.

It is not recommended to revert a profile to an older Firefox version because in some cases specific database (sqlite) files are upgraded and can get corrupted if you downgrade Firefox.

You should do the integrity check like I posted above.

Note that you can look at uBlock Origin as a replacement for Adblock Plus to see if that works better.

• https://addons.mozilla.org/firefox/addon/ublock-origin/

cor-el said

You can set what suggestions show when you enter an URL in the location/address bar bar via Options/Preferences -> Privacy & Security

• Address Bar: When using the location bar, suggest:
  History
  Bookmarks
  Open tabs

These are all enabled

cor-el said

It is not recommended to revert a profile to an older Firefox version because in some cases specific database (sqlite) files are upgraded and can get corrupted if you downgrade Firefox. You should do the integrity check like I posted above.

---

Note that you can look at uBlock Origin as a replacement for Adblock Plus to see if that works better.

• https://addons.mozilla.org/firefox/addon/ublock-origin/

Indeed, That is why I renamed the cache and profile folders to .old after uninstalling v56 and before installing v54. For all intents and purposes reverting to v54 was a clean install.

Also, I can't do the integrity check because about:support and about:profiles pages do not work.

I think I will restore from an old image using v54 where there were no problems and just update the programs I've updated. Macrium creates full boot drive images weekly which I keep for a year...

I should have thought of that sooner.... I'll let you know how that goes.

Can you confirm that there aren't special character in the profile path like the forum link you posted in your question?

Physical path to the profiles folder..

C:\Users\Tanya\AppData\Roaming\Mozilla\Firefox\Profiles\dud627xb.default

Profiles..ini

[Profile0] Name=default IsRelative=1 Path=Profiles/dud627xb.default Default=1

Did you check for issues with the places.sqlite database?

If "Verify Integrity" on the "Help -> Troubleshooting Information" (about:support) page or Places Maintenance can't repair the places.sqlite database then remove all places.sqlite file(s) in the Firefox profile folder to make Firefox rebuild the places.sqlite database from the most recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created
• http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Thanks for your response.

Again, I cannot access ABOUT:<ANYTHING>

That includes config, support and profiles.

Anyway, I'm about to restore my system to an earlier image which had a working v54.0.1 on it.

I will get back to you shortly with how that went.

Ok, that solved the problem Back on Firefox v54, with all the add-ons, including AdBlock working perfectly. I can now type stuff on the address bar and it works as expected.

I'll have a play around with uBlock Origin on my test PC and see if it works. Assuming no issues, I'll look to migrate all PC from Adblock to uBlock.

thanks for your help.