>> I'm now leaning toward sort of hardware faults like bad main memory, bad
>> cache or inreliable SCSI cable because your symptoms sound
>> inconsistent and varying. 
>>
>
> Yes, I think thats more likely too...but what to do about it?  
> ...
>
> I do have another Maxine.

If the two reveal the exactly same trouble, I can not provide better
way than PROM 't' selftest command expecting PROM can spot out
any hardware fault.

But, if the two behave 'differently', then try to move the disk of
troubled system to another MAXINE and see whether you can 'implant/repeat'
your problem or not.  Swapping SIMM and/or CPU daughter card are next
candidates.

Tohru Nishimura
Nara Institute of Science and Technology