Using internet explorer I log into my account. It tells me the login is successful but then redirects straight back into the login page & I'm not logged in. I eventually get in.......but it takes an awful lot of goes to get there.
I am currently using safari & am having no login problems, I only get this with IE.
I also forgot to mention on the occasion I do manage to get in using IE, it's logged me out after a minute or so.
You don't state your McAfee application versions & operating system and service pack and version of IE but if it's IE7 or 8 (it should be the latter) go to Tools/Internet Options/Advanced and click Reset.
OK and prompts and click Apply and OK. Close and reopen IE.
Go to Tools/manage Add-ons and re-enable all the add-ons and see if that helped.
Also check for malware.
Download, update and run the free versions of these two tools and let them clean everything they find. reboot if asked to.