I've had a chance to look through your malware thread, and I think I have a better idea of what inzanity has already asked you to complete.
I have a few different suggestions for you to try. It's important to note that some of these suggestions may cause you to lose access to customizations made by yourself to settings, passwords, etc. If you have settings that you need to keep on your Internet Explorer than please do not try those steps that I've outlined. I have tried to make sure that I've included warnings for the suggestions that may cause this to occur.
With that said please proceed with the following:
Lets try to add forums.whatthetech.com & whatthetech.com to your Trusted Sites list in IE.
go to Tools
> Internet Options
> Trusted Sites
Add the following two sites: forums.whatthetech.com and whatthetech.com
After adding the above two sites to the Trusted Sites list in IE try and log into the forums here at WTT to see if you are able to log in successfully.
If you still have no luck with the above try the following:
Go to Start > All Programs > Accessories > System Tools > IE with no Addons
Are you able to log into the forums successfully?
If your still not able to log in successfully try the following:
Launch Internet Explorer > Tools > Internet Options > Advanced Tab > Click Restore and then click Reset > Apply and then click OK.
Performing the above action in Internet Explorer will essentially reset your Internet Explorer settings to default. This means that they will be the same settings as when it was installed on your computer.
If you choose to delete personal settings you will delete any previously stored cookies, form data, passwords, or previously installed browser add-ons.
When you reset Internet Explorer to its default settings you will not have your favorites, feeds, web slices, and a few other personalized settings removed.
Resetting Internet Explorer's settings is not reversible. After a restart of IE, all previous settings you changed/customized to your liking will be lost, and they CANNOT be recovered.
Let me know how you make out!