Disk I/O Error Message

I have a PowerEdge 4300 with four 9 GB hards drives configured as RAID 5.   Whenever I boot this server, after the POST and immediately before the Windows splash screen, I get a message that is something to the effect, "Disk I/O Error...Status - xxxxxxx".  This message displays and disappears so fast that if you blink, you'll miss it. The system then boots and runs normally.  I want to put this server into production, but I'm a little hesitate to do so until I resolve the cause of this message.

Any help would be appreciated.