More Extreme Colors Than Usual

Friday, a friend borrowed my computer. When she gave it back to me she noted something was wrong. All the colors are more extreme than usual (this is hard to describe) but like everything has extreme contrast and is neon-ified. I saw she had downloaded a document in my firefox history which had a joker next to it.. so I thought it was a virus but so far VirusScan has found nothing and my college tech people thought it wasn't a virus and that some how all my colors are just messed up, however, when the computer first turns on everything looks normal for 3 seconds... has anyone experienced anything similar to what I am attempting to describe? have any possible solutions?

Thanks

thank you so much... sadly a techie worked on my computer for two hours today and didn't think of that!!!