Crossfire HD3850s, RAID 0 and COD4 crash?

I have been running two crossfired HD3850s for a while mainly to support Call of Duty 4 online play. I also run two HDDs in RAID 0 for redundancy. I took an automatic update via microsoft for just the drivers for the cards not CCC. Since then the PC runs fine but when i open up COD4 the graphics crash, i get a VPU recovery pop up box and the graphics run badly until i restart. When i di I always find the array has degraded and has to be rebuilt. However if i restart the PC and go to COD4 or go to it straight after intial boot up I don't get he problem - I'm foxed. I was Ocing the CPU by about 30% but recently went back to stock settings - same problem under both circumstances. Games run for ages without problem so I don't think that this has anything to do with cooling ( I have water on the NB, CPU is air cooled well). I can't work out whether this is a RAID problem or a graphic problem. I have tried several drivers and CCC versions (about 5) all for 2008 but no change. I finally went back to the late 7 series from 2007 which at the time i never had a problem with but now i still get the same crash.

Any suggestions?????

Cheers
BF

E6750 not now OCed
Ausus Maximus Formula
Water cooled NB
500W PSU
Air cooled CPU - sink and 2 fans
Armour case
2 HD3850 256Mb grpahics in Crossfire

Thanks but I've already unistalled the drivers from ms and tried several from the amd site but all the ones I've tried so far don't improve the situation. I might try driver cleaner and areinstall incase there are any fragments left after normal uninstall