Driver IRQL not less or equal?

[mrweaver]

Been using Win XP since november without any problems. Yesterday got a BSOD stating "Driver IRQL not less or equal" with a "stop: 0x000000D1 ......" message. A restart results in a screen asking to check the disk for consistency. If this is allowed to run it gets to about 3%, the disks make a prviously unheard thrashing noise and then the original BSOD "Driver IRQL..." etc. If the disk check is cancelled before it begins, I am able to get to desktop and the computer works normally unless I try to do a defrag or use WinCleaner. Then the computer goes to the BSOD as above during the analyse portion and the disks (running RAID 0) make the thrashing noise just prior to the stop. A look at the device manager under SCSI/RAID Host controllers shows a " interupt request 05 not available" under conflicting device list. Any ideas on what to try?