Problems with my Geforce4 Ti4600

What I'm currently running:
Visiontek Geforce4 Ti4600 (with the only Visiontek drivers for it)
Athlon 1.2 Ghz
Iwill KT266A-R MB (Raid currently disabled)
Soundblaster Live
512mb Ram
300 watt power supply
Running XP

Now, I've been experience a myriad of problems since I installed my card 2 weeks ago.

Problem 1:

I can boot up my pc with out a problem, when I shutdown is when I start running into my first issue. After powering off my pc and trying to turn it back on, all of my drives (hard drives, cd-roms, floppies) page constantly and my system will not boot. I can bypass this problem by waiting 20-30 minutes with my pc and try booting again and it will load with no problems. The other solution involves removing my vid card from the agp slot for a second and putting it back in, and again my system boots fine.

Problem 2:

Specific game problems - When I attempt to launch either Max Payne or Heroes of Might and Magic 4 I simply watch the loading screen and then I am dumped right back to my desktop with no error messages. This occurs regardless of the specific video settings I have setup (ie: everything turned off to everything turned completely off and every variation between).

Problem 3:

This is my most recent problem, and it occurs at just about anytime, but most notably when I am browsing my harddrive through my computer, or playing Dungeon Siege. Roughly every thirty minutes (sometime much less or slightly longer) XP spits out a File Exception error or my system simply reboots(not a overheating issue).

Any help with any of the above problems would be greatly appreciated.