This system has an Intel DQ35JO mobo with two WD 320 GB hard drives configured in a RAID 1 array. When the system was brougt to us, it was infected with malware. My technician connected each of the hard drives to another computer to begin the malware removal process. He used SuperAntiSpyware and Malwarebytes to remove what they could find. When the hard drives were installed back in the computer, he got a boot error "C:\windows\system32\hal.dll-missing or corrupt", and the system would not boot. I disconnected the drive on Port 1 and the system booted successfully to the drive on Port 0. The Intel Matrix Control Manager saw the RAID array as degraded of course. I turned off the computer, reconnected the non-booting drive to Port 1 and rebooted; the computer booted sucessfully and Matrix Control Manager began rebuilding the array. Why did the computer give the hal.dll missing message and not boot, instead of booting automatically to the drive with the good OS on it? I have limited experience wth RAID arrays, but is that not the purpose of a RAID 1 array?