single precision arithmetic doesn't seem to work right on a 4D/120GTX

[DIXONS]

Steve-
I just tried your two single precsion test programs on our 120GTX and found
no problems.  The answers are correct every time.  I would guess that
you have a bad floating point chip in one of the processors.  This would
explain why you sometimes get the correct answer and sometimes don't (as
you switch from processor to processor).  It may also be consistent with
the error rate seeming to be a function of system load (since this could
affect how often you switched).  I have a friend who had a bad FP chip
on a 70GT which caused fairly subtle problems and took a while to detect.
Good luck.
Scott Dixon (dixons at smithkline.com)