Almost all SCSI woes I ever had could be traced back to a cable that's gone bad or SCSI termination. Since we could assume that this was a working machine at one time, the termination should be right unless it's come loose from the end of the cable. The drives themselves can often be set to supply termination, but I would guess that's not being done based on what was described.
It is possible that during the move, one or more SCSI address jumpers fell off the drives and that two drives are now at the same address or at the address of the controller. This could definitely cause the behavior you're seeing.
Case: Enermax CS-A106USB
P/S: OCZ OCZ700GXSSLI 700W
Motherboard: ASUS P5N32-E SLI
CPU: Intel E6300(idle 35C/load 39C)
RAM: OCZ Platinum Rev 2 DDR2 800 MHz (4 x 1GB) 4-4-4-15-T1 (2.1v)
Hard Disk: Seagate 2x250GB SATA ST3250620AS in RAID1
Monitor: Mitsubishi DP900u
Graphics: BFG GeForce 8800GT PCI-E
Sound: SoundBlaster X-Fi Fatal1ty
Speakers: Klipsch ProMedia v.2-400 4.1 speakers
Optical: LiteOn 16X DVD-ROM; Sony DRU-710A DVD-RW