linux/raid error: sd 1:0:0:0 rejecting i/o to offline device

We have a poweredge 2500 that we replaced all of the hd's in. built a container, cleared the drives and installed the OS (Linux FC 5 with all updates to newest kernel etc). It will stay up for a while then it starts printing this message on the console.

sd 1:0:0:0: rejecting i/o to offline device

then you can't access anything.

If we reboot it works fine from 10 minutes to a couple days.

We have actually rebuilt the system 3 times now with different versions of FC3/4/5 to see if it made any difference, it didn't.

This machine ran linux (red hat 7.3 for 3 or 4 years without any problems, until a HD died).

We have also recently installed the same version on a 2800 poweredge and have had no problems at all.

We replaced the drives with the identical kinds of drives that were in there.