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!

That did not get rid of it. I haven't tried deleting and reinstalling firefox, but I doubt that that will fix it. However, I am going to try that now.

Did you try all 7 of those?

How do I get rid of malware? says:

If your anti-virus and anti-spyware software hasn't detected malware, scan your system with the free malware scanning programs listed below. You should scan with all programs because each program detects different malware and make sure that you update each program to get the latest version of their databases before doing a scan.

No, I did not try all of them. However, I uninstalled and reinstalled firefox. That did not stop the Bitdefender corner window from popping up first thing, but it did make it active so that I could click on it and it would take me to the Bitdefender webpage asking me to scan my computer. I will try running all of the malware programs that you suggested.

Bitdefender QuickScan Web Netscape Plugin is showing in your Add-ons>Plug-ins. You should remove it from there.

See it in your More System Details above.

It never occurred to me that it might be a plug-in. I clicked on "disable" and that appears to be the fix. Thank you for your help.