This is going to be one of those hard to find solutions. Let me sum this up a bit:
Vista freezes (hard lock) frequently, and XP does as well, but a bit less. This sometimes includes BSOD.
All memory timings, frequency, and voltage have been checked, confirmed, and adjusted where needed.
The RAM passes memtest86+.
I have to think this is either a RAM or MB issue.
If you don't have the latest BIOS that might help:http://www.msi.com/index.php?func=downloaddetail&type=bios&maincat_no=1&prod_no=1478
Here is a link to the MSI support forums:http://forum-en.msi.com/index.php?board=47.0