does it do this in Safe mode?
if no, examine Device Manager for conflicts w/new video card?
if yes, what do you think trying a different mouse?
you have usb or ps2 mouse? you have wireless mouse?
you are saying you have checked in device manager and have no yellow bangs or exclamation points?
not to be a wise acre, but here is XP Help about Safe Mode, in case it helps:
In the Shut Down Windows dialog box, click Restart, and then click OK.
When you see the message Please select the operating system to start, press F8.
Use the arrow keys to highlight the appropriate safe mode option, and then press ENTER.
If you have a dual-boot or multiple-boot system, choose the installation that you need to access using the arrow keys, and then press ENTER.
Notes
In safe mode, you have access to only basic files and drivers (mouse, monitor, keyboard, mass storage, base video, default system services, and no network connections). You can choose the Safe Mode with Networking option, which loads all of the above files and drivers and the essential services and drivers to start networking, or you can choose the Safe Mode with Command Prompt option, which is exactly the same as safe mode except that a command prompt is started instead of the graphical user interface. You can also choose Last Known Good Configuration, which starts your computer using the registry information that was saved at the last shutdown.
Safe mode helps you diagnose problems. If a symptom does not reappear when you start in safe mode, you can eliminate the default settings and minimum device drivers as possible causes. If a newly added device or a changed driver is causing problems, you can use safe mode to remove the device or reverse the change.
There are circumstances where safe mode will not be able to help you, such as when Windows system files that are required to start the system are corrupted or damaged. In this case, the Recovery Console may help you.
