the mouse pointer is constantly jumping.

did you try another mouse ?

try to check you hard drive and ram

also try to disable any unused process that running

Or if the mouse is optical check if you have some dirt (hair) at sensor or try to use mouse on different surface (non-reflective).

Hi,

Please advise if you are using a wired mouse, or wireless.

Please also advise if this is an optical, laser mouse.

If  it is an optical or laser mouse please make sure that the surface you are using the device on is not reflective as this may cause issues.

As suggested by other posts, check for dirt or grime near the sensor.

If all this has been checked do you have a spare mouse to try and swap it over to eliminate the possibility of the issue being the machine rather then the mouse.

Wireless Mouse:

If the device is a wireless mouse, please make sure that there are no metal objects (or any Objects) that may be blocking the eye of sight between the mouse and the receiver.
Conflicts in Software:

Have you recently replaced the mouse? if you have specific drivers or applications for a previous mouse installed this may cause this issue.

I know of one instance where an intellipoint software pack was causing a mouse to "jump accross the screen"

Hardware:

Failing hardware can also cause this issue, faulty RAM or a CPU on its way out can cause these issues, Please try running Memtest86 and burning the ISO to a disk and booting to the CD rather then the Hard drive to perform a few tests on the RAM. (Memtest86 is free and available from the links section of my post)

Please let me know how you go with this issue,

Links:

Please see the below link

http://support.microsoft.com/kb/321122

http://www.memtest86.com/

thank you

Please read previous posts before commenting and do not duplicate answers.
I had s small "fight" with EE moderator posting identical answer 10 minutes later on opinion question. That was the time I have spent to type the answer.

And pckonwar, you have accepted not first or second, but the third comment posted 4 hours later, which suggested to use mouse on non-reflective surface....