The Windows XP nv4_disp infinite loop problem is a problem people running with Nvidia graphic cards may experience on rare occasions during gameplay or even during boot on Windows XP (perhaps also on other Windows versions). Usually the problems results in the blue screen of death (BSOD).
Contrary to what most people think, this problem isn't driver related. The problem is hardware related, and it's caused by either faulty hardware (the Nvidia card) or bad connection.
In most cases the Nvidia card isn't defect, but the connectors needs cleaning.
Here's the solution: Remove the Nvidia card from the slot. Clean the connectors using a dry and clean cloth. Get a hold of a small brush where the hairs are hard and clean inside the (pci-e or whatever you are using) slot (back and forth a couple of times). Reinsert the Nvidia card and make sure it is connected properly.