Having the same issue - all my drivers/bios/RST etc. are up to date. I am running a 6-drive RAID5. All was well until I restarted following the May 2011 Microsoft security update.
One drive disappeard from the array, hanging up the ICH10R's bios. I pulled the drive leaving it degraded. I tested it and it passed, including a surface scan and a reformat.
Replaced it into the RAID port, and now it is showing as an internal disk outside the array, but the usual links to rebuild the array to this drive are missing in the Intel RST console. It will successfully mark as a spare drive, but there is no rebuild started when I do.
I am running Win7-64bit on a Gigabyte X58A-UD5 Rev 0, 12 GB memory and a mix of Hitachi Deskstar and WD Caviar Black 2Tb drives in the array. It was one of the WD that had the problem.