Hi Erik,

Yes, a single bit can disable the watch dog, but it is a timed access bit, that is you have to write a AAh to the TA SFR, then *immediately* write 55h to TA, then you've got three machine cycles to write the watch dog control bits. These bits include the WDT reset, the WDT system reset enable, and the WDT interrupt flag. It's not as unprotected as it sounded.

As I said in my previous post, I had done just as you suggested, minimal code to see if reset would work at all or if there might be some hardware problem or whatever. I *can* get it to reset...but when I added more code it stopped working. I can see serial interrupts that were active prior to the WDT timeout stop working. It's like ite reset but this time the PC isn't at 0 so it goes off into never-never land.

I am now in the process of going back to the minimal code and going over it with a magnifying glass to try to see what's going on.

Dennis