Well, looks like you wanted to downgrade iTunes for some reason? Maybe because of the stupid "bullying tactic" to upgrade to the $20 app for your iPod Touch? I don't know. But for some reason, some people might experience some sort of errors/bugs in their current iTunes version.
To completely remove iTunes from your PC, follow the instructions here:
Then get another version of iTunes and install it.
-> iTunes 7.4.3
-> iTunes 7.5
-> iTunes 7.6 (will someone tell me what's the link?)
-> iTunes 7.6.1