Someone PLEASE help with Itunes

Hi,

I have a problem when trying to install iTunes on my laptop from what i have read up on, there seem to be alot of issues, but none the same as mine...so hear goes!

When trying to install iTunes 8, it gets right the way through the installation process but when it come to registering the product, an error pops up saying that their is an issue with the key and starts to 'roll back' the installation.
I give it a few seconds and it pops up again to try and install so i click 'allow' and iTunes installs...

when i go to open iTunes and connect my Ipod touch it does not connect (show up on iTunes for me to put music on) and advises i uninstall and re-install, i have tried doing this on several occasions and im going round in cercles.

I would REALLY appreciate any help you could ive on this matter because i asked the store i got the ipod from and they just say to contact apple.

Thanks in advance

Ryan