ITunes 10 Help-Windows Vista?

Lately I have had trouble with my iTunes 10. I run on Windows Vista. I have uninstalled and re installed iTunes many times, but just cannot get to the bottom of this. When I double-click to open iTunes from my desktop, a window pops up saying "installing iTunes, please wait." This always happens, and even though I have already installed iTunes numerous times, I still get this message. It takes a long time for it to load iTunes. When I get on iTunes, I can try and play a certain song, but no song plays. The buttons change from play to pause, but the scrubber never moves. Also, I am having trouble syncing my devices. I own an iPod touch and an iPhone. I CANNOT sync my iPod no matter what I try. It won't sync songs, or anything. It says, "You do not have the authorization to sync this device. Try an repair on iTunes in the Programs and Features section." Well, I own the device, and it has synced many times on this computer with older versions of iTunes, and I have "repair" many times, too. When I try to restore it, it says "You do not have the privileges to restore this device." What the heck? I bought my iPod with my own damn money, and have been syncing it and restoring it as I please before this stupid iTunes 10 came out! Same goes for my phone. At this point, I'm never buying an Apple product again...I just need help fixing my iTunes for good. And no, I am not shelling anymore money to Steve Jobs for quality support from Apple. Please! I'm desperate here!