Mine is single disk.

When I raised the problem with support they asked me if I was using a third party kernel, which I am (mlord's Hijack kernel). They recon that the problem is being caused by mlord's stuff masking irqs for longer than the standard kernel.

I have my suspicions that if I didn't have mlord's kernel installed I would probably see the "no harddrives contact support" message instead of the "failed to unmask ide" message...

Anyway, it's not a significant problem from my point of view.