diff lock from hell

[Chris Covington]

So I came into a situation 2 nights ago whereupon my diff lock was needed,
and once engaged I gained the traction I needed and all was good to go...
EXCEPT the diff lock wouldn't disengage, no matter how many times I hit
the switch, and no matter if the light on the switch was illuminated (not
the green light in the diff diagram which was always on, but the yellow
crescent-shaped one on the switch itself).  So figured, no big deal, that
driving home would force the diff lock to automatically disengage above X
mph anyway, well, no the diff lock was engaged even at 70mph.  Once
getting home, after shutting the car off and restarting it, I was able to
turn it off, and that seemed to be the end of that.

So today I get in the car, fire it up, and I see the Anti-lock off light
again, then the green diff lock light in the diff diagram, hmm.. it seems
that the diff lock has engaged again.  I was able to turn it off (ABS
was re-enabled, the green light was off) and get where I was going with
the diff unlocked.  I think it was physically unlocked too, the car
didn't feel squirrely or scrub the tires around corners.  So on the way
home I fire up the 200q20v again and what do you know, it's engaged and
I can't disengage it.  I tried shutting the car off, back on, and
immediately disengaging it but this didn't work, so it seems I'm
perma-difflocked now.

Has this happened to anyone before?  Also, when that yellow
crescent-shaped light is illuminated on the diff switch, is the diff
supposed to be on or off?

Chris
'91 200q20v