Yes, 29gb free.  As mentioned, additional entries were made to the error log after the 9002 occurred.

Yes. By the time the developer reported the problem, the log file had already been backed up (backup job runs every 30 minutes) and was in good shape. 

Additional entries...

We have seen this -- like a mirror of each other -- when the stepping is different on the CPU. We had to replace one of the CPUs to...