If you see "hda: Lost Interrupt" on the serial port, does that mean for sure 100 percent a hardware problem with the disk drive? (Cable, etc.)

Or could it theoretically be a software issue?

Reason is: I haven't until now had any reason to suspect disk trouble recently. But I'm messing around with Alpha 6, the latest Hijack, emphatic, and gpsapp, trying to get them to play nice together. I need a fairly large reservecache setting for gpsapp an emphatic to cohabitate peacefully, but the database rebuild code in Alpha 6 seems to be unhappy with reservecaches and causes kernel panics. While messing around with this stuff, I sometimes see the "Lost Interrupt" message on the serial port while it's building the databases.

Normally I would go by my own advice and say "yeah, it's hardware", but I've got a lot of new variables here all of a sudden and I don't know what to think.