I am using a 3 year old MSI P35 Neo2 FR (MSI 7345) motherboard with 4 sticks of 1GB Corsair XMS DDR2-800 RAM. The 7345 started to have problem when all 4 sticks are inserted - I can't remember since when the problem started to surface.
Symptoms include - system hang at "Initializing USB Controller..." during boot-up; IO error after boot loader phase; hanging at Windows start up screen (or during Linux boot-up, showing some ata device IO errors); RAM error during boot-up check (as shown by on-board diagnostic LEDs); disk IO errors after booting into Windows, etc.
The problems seem unpredicatable, and I have spent a lot of time troubleshooting these problems. I went for RMA and replaced my motherboard eventually, but the problems still persist.
In the end, I discovered that once I turn off the Quick Booting option in BIOS, the problems seem gone. Still need to monitor for a bit longer to make sure it is indeed the solution.
And, I shall never buy another MSI board for my next PC.