RAID array degraded - "missing hard drive"

Hi guys,

I have an Intel RAID array on my PC with 3 750Gb physical drives. I have
checked all the connections in the box and all seems well.

The error I receive is that the RAID array is degraded ("missing hard drive"
error) on port 1. Ports 0 and 2 are fine representing the other 2 drives.

This happened once before and apparently the cause was iTunes mpeg files
play havoc with RAID arrays so I've deleted anything that uses iTunes
including the application.

No matter what I do I can't get this RAID to rebuild itself. The Intel
software gives me no options to change anything ("No actions availabe").

The PC is constantly churning without any instruction for it to do something
and the performance is woeful despite being a Core 2 Quad processor, 4Gb
memory- would this be due to the degraded array?

Also on a separate note, my D drive has disappeared - this is the DVD
player. I checked the connections on that and they seemed fine also.
Wondering if this is somehow related.

Any ideas - I"m new to arrays