SCSI Boot Error

[blackbob@wwa.com (Johnny B. Goode)]

I have a Quality Computer 40 MB drive connected to a Apple SCSI card to
my IIgs, and a couple of days ago, it stopped working.  Starting
a couple of days ago, When I issue "PR#7", it says "SCSI Boot Error."

A bit of background:  For the past ten days, I've had the system powered
on continuosly.  I remember doing this years ago with my IIe, so I
assume this is not the problem, though I understand IIgs's over heat often?
Also, the night before this happened, while I was using ProTERM, 
suddenly the disk was accessed for a couple of seconds for no reason.
The next time I accessed the disk (the next day, when I rebooted) it
gave this error.

I checked all of the cables and everything appears to be fine.  Any
suggestions on where to go from here?  I would like to see if it's
the disk or the card that's bad.  I don't have anything to switch with,
though.  For what it's worth, the disk makes all of the familiar sounds
and the card does not appear to be damaged.

--
Cheers, Terry Murphy