When the mouse freezes, is there any hard disc drive activity on your PC - if there is you should be able to hear the disc spinning and / or see the HDD LED flashing etc ??
If so, it could explain why the mouse freezes and could POSSIBLY be connected with the Windows file indexing service ( "Find Fast" in earlier Windows versions ).
Try disabling the Windows Indexing service temporarily to see if it makes any difference :
Double Click "My Computer"
Right click your "C:" drive.
Click "Properties" and then
Clear the tick from the check box for "Allow Indexing Service to index this disc for fast file searching"
Click "Apply" and close the window.
Hope this helps.
If it doesn't then you can always re-enable the service.
Coconutty,