Thanks for the reading, and the good advice. What you're saying is generally correct, and it is always possible that I have flatly missed something on the return from interrupt.

However, the interrupt scheme is the DT instant interrupts include files; it may be a little roundabout but it works in general. And while interrupts do need to be short and quick, I did use exactly this code, statement for statement, in the 2.60a compiler and it worked perfectly for other PICs.

I do need the preciseness of running the code on the interrupts. I normally use flags to the main routine as Henrik suggests when I can, but this needs the timing precision, and equally important, not having a second interrupt happen while the actions are being taken.

And, as I mentioned, I recoded the logic into other (longer and clumsier) statements, and it started working. That was the one that got me. It appears that the single statement was what was throwing off the timer interrupt. It looked like it made the ISR miss the service interval, and let the timer count through its full 16 bits instead of being reset. And removing that one statement made the longer and clumsier coding work.