Macbook pro trackpad stops working after plugging in USB mouse in Windows 7 under bootcamp

A great way to rule out hardware versus software issue is to create a new user and see if the problem still occurs when logged into the new user.

System Preferences>Accounts> + (may have to unlock first). For ease of use, I'd make the new "test" account an administrator. When you are done, log out and back into your regularly used account. System Preferences>Accounts> - (delete home folder and all contents).

If the issue persists, it should be related to hardware and not software.

Hope that helps!

Have you tried using other mice, either the same make and model or another brand altogether, and do they exhibit the same problem? If not, then you probably have a hardware failure with your mouse.

Beyond that, what have you changed or upgraded or installed on the Mac side just before this problem appeared? What have you changed or upgraded or installed on the Windows XP side just before the problem appeared? There must be something. This is the key to troubleshooting.

Reset the PRAM.

If that does not help, report back.