386i Screen Freezing Problem

[Stefan Mochnacki]

I have a 386i Roadrunner 150 (20MHz, no cache 8MB), with my own CDC
Wren IV 300 MB drive and 1152x900 color graphics. I have a peculiar
behaviour which has not disappeared with the replacement (for other
reasons) of both the mother board and memory board:

Every two or three minutes the screen freezes for three or four seconds,
sometimes with disk activity and heavy CPU activity.  Keystrokes typed
during the screen freeze appear only when the screen un-freezes.  No other
users are logged on and nothing unusual is going on. It may or may not be
associated with the "sync" which occurs every 30 seconds; usually syncing
is much faster. This happens even with no DOS windows open. 

My Sun service guy is mystified. Before I spend more of my own or some
higher-up Sun engineer's time tracking down this annoying behaviour, can
anyone explain it ( and maybe fix it or tune it out)?  My colleagues using
a 3/110 and a 386i RR-250 (both 1152x900 color) don't experience it. It
happens under 4.0.1 as well as 4.0.

Stefan W. Mochnacki          INTERNET - stefan at helios.physics.toronto.edu
Astronomy, U. Toronto        UUCP - {uunet,pyramid}!utai!helios!stefan
+1 (416) 884-9562            BITNET - mochnacki at utorphys.bitnet