Microsoft is notorious for messing up computers via the driver updates for the video and sound cards (possibly others).
In Windows 7 Professional you can tell Microsoft not to update drivers, as follows:
Press "Start"
Right click on "Computer" (if your "Computer" is not a selection, then enable it in the task bar settings)
Select "Properties"
In the dialog that opens, select "Advanced System Settings".
Select the "Hardware" tab.
Click on the "Device Installation Settings" button.
There is where you can tell Microsoft to never install driver updates, or set your own configuration. By default, they install driver updates.
