Hi mikel,
I faced the same issue once. Here is the solution
1. Power up the board & press RESET switch for 30 seconds & release it.
2.Now try to program your controller.
3. If you find the same problem then see the oscillator value in the tools setting, the value shouls match external oscillator value used.
Kindly let me know which tool are you using for dumping the hex file in controller. Furthe quries please share.