Ok, your post is quite old but I am new here and thought maybe I'd try and help you. 1st off assuming this is a full licensed copy of Maya and it's not a cracking/hacking issue then it may very well be the video card or bad RAM if the computer reboots. If it only happens with Maya then you may want to check here:
http://www.aliaswavefront.com/en/Community/Support/qualified_hardware/QUAL/maya_45_NT.html#cards for the Maya qualified hardware. Game cards make BAD workstation cards and vice versa. Maya likes, enjoys nad oprefers Hardware overlay planes extensions which your card does not have. That may be part of the problem. hope it helps.