Need help! New PC freezes when I run PT LE

[Rober50]

I just had a reputable computer shop build my new computer strictly for studio use, but now I can't get Pro Tools LE to run consistently. Sometimes the PC shuts down when I click on the Pro Tools icon, but more often it lets me open a session and then freezes up. After 8 or 9 tries I can acually run a session, but if I shut down Pro Tools I have to go through the process all over again. I've followed the instructions for installing hardware/software and configuring my PC, and have also referred to the trouble-shooting guide, but the problem still exists. Any hints? My system is:

Digi 001
Presonus Digimax
Pro Tools LE V 6.4
Windows XP Pro (SP1)
ASUS A8N-VM MB
AMD Athlon64 3200
3X120GB SATA Drives