If it's telling you that file is missing or damaged, your disk is seriously broken. You should never install your OS on RAID 0 - if any of the disks goes down you lose the whole volume, doubling (at least - for 3 disks your chances triple, 4 disks quadruple etc) your chances of a catastrophic failure. If you really mean RAID 0, striping, not RAID 1, mirroring, you'll be out of luck. The file is vital to Windows - it contains the HKEY_LOCAL_MACHINE\Software registry key. If you meant mirroring, RAID 1, if it's software RAID 1, disconnect the primary drive, select the other drive to boot from in the BIOS, and see if it comes up. If it does replace the primary disk. You might have been lucky and it was a software error that corrupted the file, and you won't need a new drive. I'd replace them anyway as a precautionary measure. If this happens with more than one drive look into the general stability of your system. Don't overclock anything. Check that your drive cables are rated for the speed you're running them at and that they're intact. Replace the disk controller. Consider replacing the RAM - RAM errors rapidly become errors on disk as the OS flushes in-memory changes to the disk. Mirroring is no substitute for backups. If software writes an incorrect value to the disk, or if a RAM error corrupts a piece of data before it's written back, the OS or disk controller will happily write the erroneous value to all disks that make up the mirror. Stability. What an interesting concept. -- Chris Maunder