... appears to be that he can't determine what's going on. If, as you say, he can tell when the watchdog was the cause of a reset, he must have concluded by now that there's some other problem. After all, a watchdog is supposed to generate a reset of some sort when his code fails to "pet the dog". My first concern would be that it's executing code in undefined code space, and filling it with NOP's would, at least, prevent a freeze, unless it's caused by an infinite loop. With a little debug effort, he should be able to find an infinite loop.

However, he did code this thing in 'C' ...

RE