I was at my sisters place this thursday. Her computer was acting all wierd. She had also started to have problems on Facebook a few days ago where the dynamic interface functions of Facebook suddenly began to throw errors... (javascript errors)
The word on the street is that a new kind of Facebook virus is out there to get us. I don't really know any details on that. My sister, however, had been searching the net, and from the huge result set of sites about "Facebook virus", she was getting a bit nervous.
We tried three different virus / trojan cleaners, but none of these reported about any installed virus og trojan. Then it struck me that it could be something with her settings. The following change of settings is a classic within the web developer community, because it enables a developer to see the last change he/she made properly.
In Internet Explorer, go to
Tools -> Internet Options and click Settings under "Temporary Internet Files". Here you check "Every visit to the page". Click OK twice.

The default setting is "Automatically". I'm not sure about what algorithm that is behind "Automatically", but basically it all comes down to how and when to use cached items on your laptop instead of downloading them from the web page in question.
After doing this change my sisters problems with Facebook were gone.
PS. The computer acting wierd and her problems with Facebook had nothing to do with each other. But that's a different posting...