Hmm I've never seen that one. A Google search with the terms "hda" and "lost interrupt" turned up a lot of talk about laptops with flaky advanced power management support, and a few failing motherboard/memory problems. I would check the cables, but wait for someone from Empeg (or someone familiar with that particular error message, possibly someone who spent a lot of time writing IDE drivers..) to comment before you crack open your Empeg (unless it's already been opened before.)

FWIW the error message I was getting was "database size mismatch" or something like that.