I've seen other posts about mice not working properly after installing
Office 2007. What kind of a mouse is it? Are you using the mouse drivers
that came with the mouse or the ones built into Windows?
Fellow MVP, Herb Tyson, suggested this to one poster:
"Did you reboot after installing Office 2007? If not, then give that a try
and see if it helps. There might be related files that won't be loaded until
after you've rebooted.
Another thing to try... create another User account and see if the problem
exists there, too. All too often I've seen a variety of problems exist for
one User account, but not at all when I log in as a different user during
the same session (i.e., without rebooting).
Another thing to try would be to use Office 2007's Diagnose feature (in Word
2007, Office - Word Options - Resources - Diagnose) to see if you can repair
Office 2007. Something might've gone awry during the installation, and is
now affecting scrolling. "