Windows 7 Home Premium X64 - iTunes 10.5 - Not Starting

Thanks in advancer for any help...

Has anyone had any problem witrh the new version of iTunes for Windows 7 Home Premium X64?

I updated in the normal fasion and then iTunes refused to start. So I uninstalled all traces of Apple software, restarted, downloaded a fresh copy of iTunes for Windows X64 and installed it. Again I restarted my PC and tried to start iTunes. The process starts and uses 20% of my CPU power but then nothing. The process stops and nothing happens.

I've just got my very first piece of Apple kit (iPhone 4S) and I'm trying to get some music on it but I'm having big problems. Can anyone help me get iTunes working so I don't have to take my iPhone back the the shop and continue on with my Android line of devices.

Bobby