itunes 10.6 64 bit won't install on windows 7

Hi I tried installing iTunes 10.6 (latest version) 64 bit on my windows 7 laptop. It goes through to a point and then I get the following error message

unknown\components\DA42BC89BF25F5BD0AF18C3B9B1A1EE 8\5C13C3F8A3C98AA4E8AF179 2A0A75D33

Verify that you have sufficient access to that key, or contact your support personnel.

I've tried several different methods -- installing as administrator, wiping all temp files, unistalling all Apple products then re-installing fresh ones... nothing seems to work. I can download the 32 bit version of ITunes and it works, but it won't sync to my iPhone.