my curser does the same thing. it was like this from the very first day. I should have returned my pc back but I couldn't because I was in the middle of a very urgent work.
when I researched the subject I found out that it is something related to the motherboard, although I am not sure how or why. so I think you have to live with this..
on the other hand make sure that the mouse wire is not tight or tangled, sometimes it could be as easy as this.
Thank you very much for leading me to the motherboard as the root cause! I am computer illiterate; however, after discussing the mouse/cursor issue with some computer experts at work, they told me to try a mouse with a USB connection rather than the round plug mouse which came stock with my Dell package. I plugged the USB mouse in and restarted the computer and the mouse/cursor is now working great. Again, thank you for taking the time to share your thoughts. Philip.