Have a look in the startup tab of MSCONFIG.
I just did a fresh re-install of Windows 7 Professional. All programs are back in and running smooth, almost. When I log-in, iTunes starts automatically. Only on my profile. Not on the other 3 on our desktop. I also posted at Apple, but believe it's a setting in Windows. I checked every option/setting in iTunes. It's not there. There is nothing in startup on the start menu. This is making me crazy.