Do a malware check with some malware scanning programs on the Windows computer.
You need to scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of their databases before doing a scan.

• http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
• http://www.superantispyware.com/ - SuperAntispyware
• http://www.microsoft.com/security/scanner/en-us/default.aspx - Microsoft Safety Scanner
• http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy

You can also do a check for a rootkit infection with TDSSKiller.

• http://support.kaspersky.com/viruses/solutions?qid=208280684

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

Already did that. Malwarebytes found 6 infections, which it took care of. I'm not suffering from pop-ups, it's redirection from the site I'm trying to access to someplace else. Spybot is running now, but hasn't found any new infestations. I'm about ready to dump firefox, and that frustrates me, as it's my FAVORITE browser.

Such a redirect is usually an indication of a malware infection.

So if using the above listed scanners does not fix it or if you are blocked from installing those scanners then it is best to ask advice on one of the forums that specialize in malware removal mentioned in the Popups_not_blocked article.

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked