My be it is because of some lens problem, not becasue of virus ;)
Sorry i don't know about any Virus name which create such type of problems. But let me tell you some spy softwares like Subseven, which give right to some to do such funny thing with other.
Try Spybot - Search & Destroy 1.3 to detect it.
That all which i like to say regarding your question
Bye
Noman Khalil
September 2004