massbus deadlock

[David Keeffe]

Has anyone any experience of a DEC VAX 11/750 going dead
(looping in _idle) but with no reported error?
We have but one (yes one) MBA with the following on it:

0	 1 	2	3
Rm03     TU77	RM80	RM80

Problems really started with the second RM80.
I guess the problem is a deadlock between paging and filesys
access. We run a sort of 32V with custom BSD 3+ paging
like they run at Uni. of York.