First thing that I could think of is go to device manager
and look for the mouse driver
Look for any yellow warning markers
Look for a current driver at the website of the mouse mfg.
Device Manager - Finding Unknown Devices - Windows 7 Forums for vista too
Install current driver
Does not work
Try a system restore back to a few days before the problem
System Restore - How to
Does not work
Make a full antivirus scan and download and make a full scan with malwarebytes, be sure to update first
Still does not work, try an SFC scan.
System Files - SFC Command