Make sure you have the following:
Latest service-pack for your specific OS
Working and patched-up version of IE 7
ALL other windows updates!
The easiest way is by running Windows Update. Why exactly a person wouldn't be keeping their OS up-to-date (other than it being a pirate version of Windows) I'll never understand.
Oh and if you followed some "services-you-don't-need-guide" (like those by BlkViper etc.) good luck! Many of the services listed don't actually tell you EVERYTHING they're needed for in the "service description" but of course people think they can simply DISABLE them.