Window display lock broken because process xxxx blocked

[Ralph P. Sobek]

What does this message mean?  It happens to ONE of our SPARC-Stations, and
from time to time a window pops shut and disappears together with its
attached process.  This happens on the bitmap, where processes suddenly
die like this.  The only correlation that I found is the message that's in
the subject line.  It can be any type of window: cmdtool, shelltool,
perfmeter, etc.  It does not happen very often: 1 to 3 times in an 8 hour
session.

Thanks a lot,
Ralph P. Sobek