Do you have a monitor in the machine room?

IF SO....

You can take a video camera, film the I/O's, and then walk off and leave it recording the I/O screen. You can then wade through all the video footage to the approximate time of the call back, and then slow the footage down to a few seconds before the fault occured. You can then see I/O responsible for fault.

Just a suggestion.

It Don't mean a thing if it aint got that swing.

Cool, Free, Johnny Smith courtesy of NPR..HERE
http://www.npr.org/ramfiles/asc/asc25.smith.asx