Hi bang145,
Thank you for using the Apple Support Communities.
I see you've been having issues signing in with your Apple ID in iTunes on a PC. Reinstalling iTunes was a great start, and it sounds like there may be a few other factors to consider.
To clarify, are you able to sign in to the same Apple ID on your iPad and Apple TV?
Based on the description of the issue, this link sounds like your best starting point to determine if there might be security software causing the error: Resolve issues between iTunes and third-party security software.
I hope this helps you. Enjoy your day!