iTunes won't install on my computer

Hi, got a problem hoping someone could help.

Ive just upgraded my laptop from Windows Vista Home Premium to Windows 7 Ultimate, i had iTunes install on it, and had my computer authorised to my iPod Touch 4g (Windows 7 installer said it wont work and i needed to unauthorise it) True to its word, it didnt work, it also prevented my computer from shutting down and if it went into sleep mode, it wouldnt come out. I tried to uninstall it, but windows installer just hung up every time instantly.

I figured this could have had something to do with the upgrade so i formatted my HDD and did a clean install of windows 7. I downloaded iTunes, tried installing it, i noticed the installer kept doing the same things over and over again, then just hung up (the progress bar was about 85% full). Cancelled the install, checked to see if any programs were installed and Apple AutoUpdate (?) and Bonjour were installed. And funnily enough, the problems came back (hung up when shutting down and not coming out of sleep mode). So maybe one of those programs could be causing it?

Ive restored it back to before i tried to install it, all other programs work as they should.

I've tried googling the problem, but cant find anything related.

Anyone got any ideas to try? i need iTunes to be able to sync my iPod touch.

Thanks ~ Craig