Bizarre. MIght be a video driver issue. What version of IE are you using? There is a very nasty virus on the loose targeting IE7. If you picked it up from another WEB site, you could be in for a long week.
Here is the news blurb about it BMathis.
Well, Mozilla has been hacked upon pretty good recently, so do not get apathetic about your computers chances of getting a virus/worm/spyware/malware placed on it.
Since last Tuesday, Microsoft has updated its advisory four times. It expanded the list of potentially affected versions of Internet Explorer to include not only IE 7, but also IE 5.01 SP4, IE 6, IE 6 SP1, and IE 8 Beta 2. It also added several workaround options that involve disabling certain features.Microsoft however says it is aware only of attacks affecting Internet Explorer 7 under the following systems: Windows XP Service Pack 2, Windows XP Service Pack 3, Windows Server 2003 Service Pack 1, Windows Server 2003 Service Pack 2, Windows Vista, Windows Vista Service Pack 1, and Windows Server 2008.