I have an tower PC running XP with an MS-7207 motherboard and a Radeon 3850 PCIe video card. After 2 yrs, the v-card has suddenly disappeared from device manager. It reappeared twice, but is gone againg; using integrated video now to get by. Have reseated card, blown it out, etc. Restored to earlier date. No use. Does this sound like a video card problem, motherboard, or something else. Thanks.