Download a fresh copy of Firefox and do a reinstall of Firefox on top of the current version.

If that doesn't work, try a clean install.

Also do a malware check with a few malware scan programs. You need to use all programs because each detects different malware. Make sure that you update each program to get the latest version of the database before doing a scan.

• http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
• http://www.superantispyware.com/ - SuperAntispyware
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy
• http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free
• http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page

First of all you remove older firefox after that you reinstall firefox12

Firefox 12 is terrible. I cannot find where to report this problem, so I will try here. It takes minutes to load any and every webpage after I upgraded. I was surfing fine with 11 and the update offer came and I always update FireFox. But then every page took more than a minute to load. I had to go to Internet Explorer (which I hate) and find an older version of FireFox (which I am not happy about how difficult it is to find them) install back to 11. Everything works great again. The messages I got while in 12 for every website I tried (and I tired a lot) was that it was "waiting for the website", but that was obviously not what was happening since the sites loaded fine in IE and now again load fine back in FireFox 11.

Just ran the V 12.0 update and it's crashing on start-up every time. I have followed all the steps in the crashing on start-up guide. (unable to open in safe mode) Fresh install done. Restarted computer. Mac - updated Plugins updated Restarted computer again etc etc..

Running MAC OSX 10.7.3 on macbook air.

This is the only crash info I can get from the screen that comes up every everytime.

BuildID: 20120420145725 CrashTime: 1336030534 Email: FramePoisonBase: 7ffffffff0dea000 FramePoisonSize: 4096 InstallTime: 1336029854 ProductID: {ec8030f7-c20a-464f-9b0e-13a3a9e97384} ProductName: Firefox ReleaseChannel: release SecondsSinceLastCrash: 200 StartupTime: 1336030533 Throttleable: 1 Vendor: Mozilla Version: 12.0

Safari is running fine.

Any help is appriciated.

Thanks Ben

The problem (at least for me) was related to how Firefox 12 is linking to the profile after the upgrade. Running in Safe Mode does not fix the problem neither does creating a new profile or simply deleting the existing profile folder.

Here's how I fixed the problem without uninstalling.

1. [Backup Your Existing Profile] - Be sure to remember where you save your profile folder so you can restore your bookmarks, sessions, etc. if you lose the profile during this process.
2. Download the complete Firefox 12 install from mozilla.org.
3. Install Firefox 12 over the existing broken Firefox 12 install.
4. Run the profile manager - Click Start; Click Run...; Type firefox.exe -profilemanager (Firefox must be closed to do this.)
5. In the profile manager delete your existing profile. Select Don't Delete Files. This will remove the profile from the profile manager but retains the files (your settings). This step is important. You must use the profile manager to delete the existing profile.
6. In the profile manager create a new profile.
7. Start Firefox 12. It should run now, but it will not have your old settings.
8. Go to the Profiles folder. It's the same location you went to in Step 1.
9. Delete the contents of the new profile folder but DO NOT DELETE THE NEW PROFILE FOLDER ITSELF.
10. Copy the contents from your old profile folder into the new profile folder.
11. Start Firefox 12 again. You should now have a working Firefox 12 with your old settings intact.

You can try this process without Steps 2 and 3. I don't think they are necessary. Hope this saves time and frustration for someone.

Just installed beta and it seems to be working ok. I guess I'll have to wait for V12.0 issues to be resolved for MAC.