Have you updated to 4.1 yet? Matrox does not have drivers for it, and crashes seem fairly common. Might not be your cause, but worth thinking about. Seems that 4.0.1 was working OK with Matrox, but not 4.1.
Systemic crashes can be any number of things. Please give complete details on your system. The more, the better. Please include all software and versions. Running applications and Processes can be very important.
The system is built to exceed your specs.
That is certainly the case, since you have Matrox. However, I'm glad to NOT meet your specs, since Matrox have a very good reputation of screwing things up as you have noticed. You would likely have been better off with a faster CPU, more memory and better disk specs than with a Matrox, but everybody has a right to his own problems.