Stefan Sichler <sichler@rummelplatz.uni-mannheim.de> writes: 
> I've found out that the 'options DIAGNOSTIC' causes the trashed /dev/grf3
> screens.

  Ah, which I have in my kernels.

> But still, I'm not sure about the exact reasons....

  I'm wondering if the problem occurs anytime the kernel does a printf().  It seems
like each time it occurs to me, I was either doing something that did a printf(), or
something happened which resulted in a printf().  [The most recent was an informational
message from the CyberStorm Mk III SCSI driver.

  I haven't tried tracking it down yet.  My first step was going to be looking at
the kernel printf() and seeing if it does something that might interact with the
graphics chip.

Michael
---
Michael L. Hitch                        mhitch@montana.edu
Computer Consultant,  Information Technology Center
Montana State University, Bozeman, MT     USA