video card v motherboard conflict

I recently installed a new video card (NVIDIA
GForce 7600 GS) on a ABIT NF7-2SG Motherboard
Everytime the computer has to reboot for whatever reason the bootsequence gets hang up during the beginning if the post sequence.
The only way to fix the problem seems to be a complete powerdown – disconect of the monitor removal and reinstall of the video card.
what is the possible conflict. it has nothing to do with the OS (XP PRO) since it never even gets to the point of reading the bootsector it seems.