looking at the spec of that board, two things come to mind
ASUS - Motherboards- ASUS M2N32-SLI Premium Vista Edition
If you're running Win7 it may well need a BIOS update to work properly
Secondly, i see it has six nVidiia SATA ports (capable or RAID) and a single internal Silicon Image SATA port as well. Which are you using for the drives? If the SiL one I'd switch to the nVidia ones
Also is the RAID software running? if it is, but a RAIS is not actually configured that could cause similar symptoms
But -and heres the but - its an ASUS board, and an nVidia chipset. I wouldn't expect either to last more than around three years
However - usual checks
Reseat eerything, clean all the dirt and dust out. Are the fans ckean and running freely (especially the graphics card). Check the memory for faults, download and run the relevant diagnostics for the hard drive