HELP! Evil UniPath/IDE interaction (?)

[phil sutherland]

[I'm posting this to the SCO mailing list as well as comp.unix.xenix.sco.]
[Please skip if you're seeing it twice.                                  ]

Folks,

HELP. An evil problem is keeping me stuck in Sydney, far from my native
Perth.

Scenario
--------

SCO Xenix 386 2.3.2 GT
Seagate ST1162A IDE (AT interface) disk drive
SCO Unipath 1.3 with Pathway interface card

Symptoms
--------

System locks with disk drive light on, although ALT-Fx to flip screens
and indeed anything non-disk in nature still seems to work, including
a cu that was already in progress to a neighboring machine. Thus it
appears to be a disk hardware lockout of some sort. Problem occurs
randomly, sometimes even during multi-user bootup (I'd guess at about
the time snautil -start gets going). It appears to be aggravated by
intensive disk access - a /etc/badtrk non-destructive quick scan will
make the problem occur within seconds. Problem is completely solved by
unplugging the modem from the Pathway card - although for obvious
reasons this is unlikely to sit well with the customer. Thus, evidence
appears to point to some evil form of Unipath/disk interaction - maybe
an interrupt at the wrong time or something? 

What it's not
-------------

Individual disk drive or bus interface card (I've replaced both).
Individual Pathway interface card - that too has been replaced.
Bad kernel/link kit. 

What I'm thinking of trying next
--------------------------------

Different drive type (back to the old trusty ST506 or something)
Different kernel entirely - 386AT instead of GT
Deep probing the kernel with a special purpose device driver, to see
 more of what's going on.
Application of appreciable kinetic energy using an axe.

Thoughts?
---------

Has anybody any ideas on what this is, or how I might go about fixing it?
My cats are missing me... Please mail responses - while away from a local
call zone my newsfeed is severely restricted.

Thanks in advance....

-- 
+--- phil sutherland -------------< philsuth at DIALix.oz.au >--+
|       Open Access Pty Ltd, Perth, Western Australia.       |
+------------------------------------------------------------+