There is an archived thread about this -- about using the scroll wheel on a Logitech mouse with Parallels. The first scroll works fine but then the guest OS loses focus, the cursor changes to a Mac cursor, and the scroll wheel will not work again until you move the mouse and guest OS regains focus. The solution in the archived thread is to buy some shareware mouse software and do a command line hack but I don't feel like throwing a hack at the problem so I think I'll just buy a new mouse. Can anyone confirm this is not a problem with Apple's Mighty Mouse? The two-finger scroll on my MacBook Pro's touchpad works fine so I'm guessing the problem is with the Logitech Control Center (version 2.2.2, and Parallels build 3214). But if others can confirm this I'd appreciate it.