Thanks for your help! I will try your suggestion. I did notice one thing before leaving the office last night, when I remove the ADC from main everything works well. When I rerun the test using ADC enabled it screws things up. Do I need to also do something with T1CON like select a bank of memory that it can write to that is common across banks? some how I think writing to values to the timer is somehow not being read out of the correct bank at some point after the interrupt is enabled upon exit....just my guess.

Nick