Programs won't stay open & BSOD - Exhausted everything, Please HELP

Hello,
The programs on my homebuilt PC keep spontenously closing. I cannot find any correlation to when or why. I also have received several BSODs. I have noticed that if I do not turn the computer off the occurence becomes less frequent to almost never occurring. However, if I shut down the computer, when it is started again it happens ALL the time. The display in my monitor attached to the GeForce 8400 GS graphics card is also malfunctioning (vertical lines appear). I have several dump files, but I just copied the most pertinent info from the last 4 below:
9/21 event 1:
BugCheck 1000008E, {c0000005, 8054bfcb, b00a5b44, 0}

Probably caused by : win32k.sys ( win32k!HeavyAllocPool+74 )

9/21 event 2:
BugCheck 1000008E, {c0000005, bd0fad72, afd4092c, 0}

Probably caused by : hardware ( nv4_disp+e8d72 )

9/23 event 1:
BugCheck 10000050, {e6ecfbd0, 0, 8054bfcb, 1}


Could not read faulting driver name
Probably caused by : ntkrpamp.exe ( nt!ExAllocatePoolWithTag+663 )

9/23 event 2:
ugCheck 1000008E, {c0000005, 8054bfd2, b19f9974, 0}

Probably caused by : ntkrpamp.exe ( nt!ExAllocatePoolWithTag+66a )

I did the MemTest 86 and everything passed. I removed the graphics card and the problems still continued. I am completely stumped.

Please let me know what else you may need to assist me.

I am running Windows XP Prof sp3 32bit. The hardware is as follows:

cpu: AMD Phenom X4 9750
mobo: XFX nForce 750a SLI
ram: Centon 2048MB PC6400 (qty 2)
cpu fan:Cooler Master Hyper N520