I have this little problem since I updated to RC1 and SP1(Vista 32 Ultimate).. dont know what really caused it RC1 or the SP1 update.
I have used a few skins, i dont think it is a skin problem
The mouse I have is the one that belongs to a "Logitech Dinovo Cordless Desktop" But I use it with the standard Vista HID drivers which work fine for me
I just move the cursor out of the way and turn it off (it has a little switch), and use the remote to navigate through mediaportal.