Does the problem happen when you restart in Firefox Safe Mode and then click "Continue in Safe Mode"? See the Diagnose Firefox issues using Troubleshoot Mode article for help doing that.

It might also help if you could post a screenshot of the error. See How do I create a screenshot of my problem?

Also 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

Hey, I was just about to post back and suggest a malware scan, after doing some google searches and finding the reply posted by gordoalac in this thread:

• https://support.mozilla.org/questions/721712

this is what keeps popping up

and yes in safe mode the same problem is happening. Do i use all the malware checks?

i went to that site with gordoalac and it worked ! thank you so much for the help :D!

Glad to hear it! Thanks for posting back with the outcome :-)

For the record, (for others reading) cor-el also posted a link to TDSSKiller, http://support.kaspersky.com/viruses/solutions?qid=208280684 ...which was the fix posted by gordoalac in the other thread. The Anti-Rootkit Utility, TDSSKiller is also one of the malware scanners suggested in the KB article, Troubleshoot Firefox issues caused by malware.

Just to be complete, TDSSKiller is also one of the programs that I suggested in [my above post].

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

You can still use the other programs to see if they come up clean.

corel. I was editing my last post to give you credit and to link to the related KB article on malware removal, before I saw your post.