iTunes lives in a world of its own and does wacky things. It's the main contributor to keeping me from going into the Mac world.
If you've removed it, the risk is that it's zapped all your playlists etc. The better fix is the "repair" option under Control Panel - Programs. It may be too late for that.
It sounds as if something has glitched in an update. I'd be inclined to go to the iTunes site and download the latest version, and try installing that.