Do the following:
If you are using IE8 beta uninstall it immediately. Reboot.
In IE7 go to Internet Explorer Tools/Internet Options/Advanced and click Reset, Apply and then OK.
Exit IE and re-open. Re-enable whatever add-ons you need as that exercise disables all of them.
First make sure that Windows is totally up to date with both critical and non-critical updates. I trust that Vista is SP1. If not there is help with that
HERE.
Then do the following:
1. Uninstall all McAfee programs through "Add or Remove Programs" in Windows "Control Panel".
2. Use the MCPR tool, see this article:
How to remove supported McAfee consumer products using the McAfee Consumer Products Removal tool (MC... This will remove all McAfee remnants from your computer. (you must have Windows Vista, XP or 2000 SP4 to use this tool)
3. Launch Windows Explorer and delete all McAfee files in "Program Files" but especially in "C:\Document and Settings\<user>\Application Data" and "C:\Document and Settings\All Users\Application Data". You have to set Windows Explorer to show all hidden files and folders (Tools > Folder Options > View tab). Just delete the McAfee folders even if they are empty in all the "Application Data" folders. Can be more than one!
In Vista: C:\Program Files, C:\ProgramData and C:\Users\yourname\AppData\Roaming
If you find none do not worry, as it only means that the removal tool has done its job.
4. Reboot and redownload/reinstall your McAfee products directly from your account at the McAfee web site, not from any CD that you may have.
For US Customers.....
If you are McAfee direct customer, go to
https://home.mcafee.com/Secure/Protected/Login.aspx and log in to download your McAfee products.
If you received your McAfee products from your service provider, please use the list below to download your software.
Comcast users should go to
http://security.comcast.net/ and log in to download your software.
DELL users should go to
https://us.mcafee.com/root/login.asp?affid=105 and log in to download your software.
Gateway users should go to
https://us.mcafee.com/root/login.asp?affid=370 and log in to download your software.
eMachines users should go to
https://us.mcafee.com/root/login.asp?affid=365 and log in to download your software.
MSN users should go to
http://membercenter.msn.com/ and log in to download your software.
AOL users should go to
http://daol.aol.com/safetycenter and log in to download your software.