here is an image of the error message

There are several possibilities. We will have to go thru them. If Firefox only works in Windows safe mode, then something on the computer could be the cause.

• 1

Start Firefox in Safe Mode by holding down the <Shift(Mac Options)> key, and then starting Firefox. Is the problem still there?

• 2

Check the programs that are on your computer

Windows: Start > Control Panel > Uninstall Programs. Mac: Open the "Applications" folder. Linux: Check your user manual.

Go thru the list. If you find something that you don't know what it is, use a web search.

Troubleshoot Firefox Issues Caused By Malware {web link}

• 3

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

Trying shift-open did not work. I've uninstalled everything in control panel already that I didn't recognize -- that didn't work either. I've run a comprehensive scan with malware bytes, which quarantined a bunch of stuff -- but the problem persists. I've now started a Microsoft Safety Scan which says it may take several hours. I'm dubious about that but will try.

One more thing I thought of regards possible malware - about a week ago the "ask.com toolbar" suddenly appeared in Firefox. My wife was using the computer at the time and doesn't know how it got there. I removed it from the browser -- but it seems like the problem I'm now having with opening the program might have been coincidental to that. thoughts?

I ran the Microsoft Safety Scan right after running Malware Bytes. MS did not find any malware or viruses at all. But the problem of Firefox not starting in normal mode persists. I am at wits end.

Ok I ran every single one of those recommended scans. The found a lot (or seemed like a lot but maybe not) of stuff and quarantined or deleted all of it. Still have the same problem with firefox.

On advice of someone I trust who knows a lot about computers, I tried installing Waterfox browser -- but damnit if the same problem doesn't occur there as well. For now I guess it's either Chrome or IExplorer (both of which work). If you ever figure out what might be the root cause of this I'd like to know because I much prefer Firefox to Chrome or IE.

http://kb.mozillazine.org/Uninstalling_toolbars That should help with getting rid of the Ask toolbar. It probably got installed with something else that was installed in Windows. You should check every step carefully when installing new software. A checked box that says "Install ask.com toolbar" can be easily missed if you blindly click every OK button during an install without reading carefully first.