Pro Audio Support

Q:
"A system error occurred Illegal Instruction Error" when booting the Mac, followed by a corrupted OS.
 
A:
Could be caused by a virus. If an external drive is suspected as the "carrier", leave it off until booted, then mount it. If the internal drive is suspected, boot from the OS CD (or other bootable CD). In either case, a thorough scan for viruses and reinitialization of the drives is in order.