Disk error code 33

I've taken over a Proliant ML 150 with two 136 Gig Compaq drives mirrored. About once a day for the last year and a half, the Event Viewer logs a Error code 33 on HD 0. It says "Data was recovered using error correction code on device \Device \Harddisk 0. I never see the error for disk 1.

Is this just a file system problem? Do I just hit Ctrl + A at boot up and find a disk check utility? How would I run a hardware diagnostic on the drive?