OK - understood. In that case, I'd suggest an uninstall and reinstall of Itunes. If you've only just installed it, a system restore to a point prior to the original installation might also help.
Before installing, make sure you quit all unnecessary running tasks. I would shut down your virus scanner, firewall, and any other background programs you might have (obviously, make sure you are disconnected from the internet whilst in this unprotected state). Install, then re-boot, allowing all the other programs to kick back in.
See if that helps. (another option might be to download the latest itunes software and try that (if you haven't already).