Create a new profile exclusively for the 4.0 beta version and create a desktop shortcut with -P "profile" appended to the target to launch that profile.

• http://kb.mozillazine.org/Testing_pre-release_versions

• http://kb.mozillazine.org/Creating_a_new_Firefox_profile_on_Windows
• http://kb.mozillazine.org/Shortcut_to_a_specific_profile
• http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox

I had the same problem and solved it by disabling the printpdf add-on.

Some details :

• Windows 7
• Firefox 3.6.13
• printpdf 0.76

Same issue here, started early this morning. I went into Add-Ons and disabled all but the most recent version of the Java Console and then restarted the browser. (Disabled 6.0.18 through 6.0.23, leaving 6.0.24 enabled) All has been running great since then.

Nothing Works! I have this Problem since Firefox 3 to 5. Very annoying - when you download something - and Firefox freeze! You have to move the Mouse to complete the Download!

Not fixed on any version, including Aurora.

I disabled ALL add ons for 3 days, - no issues, I added them one at a time, 3 days each one, and found that when I enabled Java Development Toolkit, the issue arose during day 2, and once it happened, it consistently occurred. Once disabled, all is well. I only have Adobe Acrobat, Java Platform SE U24 6.0.240.7 and Shockwave Flash 10.3.181.34 enabled. I will continue to enable others and report if the issue comes back with any others.

This has happened to me before but seemed to be ok until today, read a few posts here then disabled Add-On Java Console 6.0.26, restarted Firefox and it seemed ok, then enabled it again, restarted Firefox and..... still ok ?!?!?! Confused the h*ll out of me but hope it helps someone else :-)

Still having this problem. Ive disabled ALL add ons, and it still happens, - restarting the browser solves it, - but it will re occur at some point during the same browser session. It has nothing to do with Java, - disabling ANY add-on will solve it, but it will return. Im starting to give up on my favourite browser, and the apparent total lack of progress in detecting, identifying or fixing the issue

I had this problem with FF 5 and FF 6 and it was driving me nuts! Until I read this forum. Then I went into Tools > Add-ons > Extensions and removed Downloadhelper, an HP Smartshopper thing, and a thing called LAILoader (www.liveblockauctions.com). Not disabled, REMOVED. My FF is now working properly. Not sure which one it was but the situation was so desperate I was using IE 9 to search for FF solutions! I suspect the LAILoader as it is an older live auction viewing addon (car auctions in my case). Hope this helps someone. I still have AVG Safe Search, Evernote Web Clipper, and iMacros for FF (great addon!) installed and working.

@doitonline - I don't think DownloadHelper can cause hanging problems. I myself use that add-on and i don't have any problems with it. It must be caused by some other add-on.

@banehawi

Clear Cookies & Cache

• https://support.mozilla.com/en-US/kb/Template:clearCookiesCache

Clear the Network Cache

• https://support.mozilla.com/en-US/kb/How%20to%20clear%20the%20cache#w_clear-the-cache

Check and tell if its working.

Disabled Java Development Toolkit, on Baehawi's post - seems to be working for now - will keep you posted. But really come on Firefox don't mess with your followers!

I to discovered that disabling all but the latest java framework stops the freezing, it also stops the youtube playback bug where every 30 sec it would pause for a sec. I did this back in the days of ff3 and am quite disappointed mozilla haven't fixed it yet!

-> Update All your Firefox Plugins

• https://www-dev.allizom.org/en-US/plugincheck/
• http://www.mozilla.com/en-US/plugincheck/

When Downloading Plugins Update setup files, Remove Checkmark from Downloading other Optional Softwares with your Plugins (e.g. Toolbars, McAfee, Google Chrome, etc.)

-> Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Check and tell if its working.

This seems to happen when an update to a Firefox extension is available. When I close Firefox and restart it, there is always an update installed and it works fine.

I am turning off "Update Addons Automatically" to see if it helps.

I am still not able to use Drop Down menus

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Check and tell if its working.