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Firefox on W7 starts but is "invisible": process runs but is unusable

  • 4 replies
  • 3 have this problem
  • Last reply by philipp

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I've used Firefox for years on my DELL Windows 7 laptop. After a recent, weekly reboot, it stopped working. By that, I mean that when I run it, a firefox.exe appears in the task manager but I can't "connect" to it. On the task manager I can see that it is using Memory and has a value for both I/O read Bytes and I/O Write Bytes (albeit these do not change after Firefox has started)

I've tried the following

Removed Firefox from the control panel & reinstalled

Renamed firefox directories ("C:\Program Files (x86)\Mozilla Firefox" & C:\Program Files (x86)\Mozilla Maintenance Service), rebooted and reinstalled

Looked in these forums and have tried solutions to problems that sound VERY similar to mine (e.g.

Did a virus scan

Ran a Malware bytes scan

Reinstalled java

Tried to run Firefox in Safe Mode (hold down SHIFT and double click on icon)

Run Firefox from the command line with various options - e.g. "firefox /safe"

Tried installing both the 64bit (as used originally) and 32bit versions

Fiddled around with profiles in C:\Users\USERNAME\AppData\Local\Mozilla\Firefox\Profiles as per various recommendations in these forums

But none of these work. Afterwards, Firefox just appears in the Task Manager (but NOT the Task Bar) and does nothing.

The only thing that does work is if I reboot my laptop into Windows Safe Mode (with networking). This allows Firefox to work but there is nothing obvious wrong with anything, so I don't know what to fix. I tried switching off Hardware acceleration in Firefox options but this made no difference once I did a normal reboot of the laptop.

My Laptop has an up to date W7 OS and all both Chrome and IE browsers work fine - as does everything else. Firefox is the only problem and then only since Monday - it has worked fine for many years up to Friday. No changes were made on the day the Laptop was restarted, no new programs installed, nothing. A colleague has a similar setup (company-dictated config on W7 laptop, same OS, Virus scanner, etc) and has no problems.

At this point I've done many reboots, reinstalls, searching for solutions but nothing works. What is interesting is that I'm not the only person to have this exact problem (see link above) but so far a solution eludes me.

Any help very greatfully received - Please Help!

Modified by route66

Chosen solution

Hi route66, Your problem is very similar to mine, described here.

The difference is that safe mode did not change anything for me.

Did your issue begin with the last version of Firefox (49) ?

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Chosen Solution

Hi route66, Your problem is very similar to mine, described here.

The difference is that safe mode did not change anything for me.

Did your issue begin with the last version of Firefox (49) ?

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THANK YOU assistance-multi

R48 worked for me - a quick sync later, and everything is back to normal.

Seriously, THANK YOU !!!

I wonder what the problem is? As I said, my colleague has a very similar setup and he doesn't have a problem. It just means, I'll no longer automatically accept new versions of Firefox - and have changed my options accordingly. I'll also hold on to the R48 install file for the foreseeable ...

A few clarifications:

  • My laptop is i3-powered.
  • When I say "Safe Mode", I am refering to the OS, not the Firefox safe mode. OS Safe mode allowed R49 Firefox to work for me.
  • I use McAfee for virus protection
  • I am using the English-Language version of Firefox

Modified by route66

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route66, glad if it works for you, although I consider it's not a long term solution.

I opened a bug at mozilla's bugzilla, hope it will be useful.

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hi route66, mozilla just released an update to firefox 49.0.2 that should fix a problem that sound pretty similar to what you've described. you can download this new version from to see if it works for you too.