System Freezes after controller error

My system freezes and requires a reboot after receiving the following message:

The driver detected a controller error on \Device\Harddisk0\DR0.

During the reboot, the C drive always needs to be checked for consistency.

I have 1 gig of memory, 1 60 gig Maxtor drive with the MS 2000 professional, 2 160 gig Maxtor drives and a silicon graphics SATA Raid controller.

I assume the problem is in the memory, the drives or the controller. I have run memory diagostics and Maxtor disk diagnostics. All diags ran without detecting an error.

Can someone help me with the following?

1. Which drive is DR0? How can I look up this information? Maybe I can disconnect the drive and see if it goes away.

2. I think it might be the controller, since it says "controller error" If I get another SATA controller ( which one would you suggest? ) can I just plug it in or do I have to reformat the disks?

Sorry this is so long. I am trying to be specific so that I don't waste anyones time.

Thanks in advance for the help