Opening certain websites with Firefox can lock up my computer, keyboard, and mouse for about 1 minute

Question

There seem to be specific "trigger" websites that lock up my computer for about 1 minute. For example, the problem can always be reproduced by trying to log onto att.yahoo.com. After waiting about 1 minute, I regain control of my computer and the website opens. There are no error messages. So far the problem does not seem to repeat after the 1st lock-up until I reboot. When I reboot, the problem happens once more on that first hit to a trigger website. This problem has been happening for about a year now. Have cleared my cache but that has not fixed the problem. Have tried using an alternate browser, Chrome, and never see this problem. Does anyone have a solution short of changing my default browser to Chrome?

Answer 1

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test.
*http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
Do a malware check with several malware scanning programs on the Windows computer.
Please scan with all programs because each program detects different malware.
All these programs have free versions.
Make sure that you update each program to get the latest version of their databases before doing a scan.
*Malwarebytes' Anti-Malware:<br>http://www.malwarebytes.org/mbam.php
*AdwCleaner:<br>http://www.bleepingcomputer.com/download/adwcleaner/<br>http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
*SuperAntispyware:<br>http://www.superantispyware.com/
*Microsoft Safety Scanner:<br>http://www.microsoft.com/security/scanner/en-us/default.aspx
*Windows Defender:<br>http://windows.microsoft.com/en-us/windows/using-defender
*Spybot Search & Destroy:<br>http://www.safer-networking.org/en/index.html
*Kasperky Free Security Scan:<br>http://www.kaspersky.com/security-scan
You can also do a check for a rootkit infection with TDSSKiller.
*Anti-rootkit utility TDSSKiller:<br>http://support.kaspersky.com/5350?el=88446
See also:
*"Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked
*https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware