Next time it goes down, ask the datacenter techs to hook up a monitor and see what it says on the console. About 95% of the time I see this happen it is due to faulty hardware. Will they consider a chassis swap for you? This way you can eliminate all hardware issues except the drive.
I had similar issues and it was my BIOS - out of date. Also that same machine passed with memtest86 and failed after 2 hours with mprime. I now test new machines FOR AT LEAST 24 hours with mprime to ensure stability. Memtest test the mem. Also check system temps - high temps can freeze things up and my Asus boards (M2NPV-Vm had a heatsink hot enough to burn me - I added a fan and some ducting to keep that thing cool, and with the BIOS and good hardware its been stable for months.