Hi although I'm pretty sure this same problem has a different source than mine,it might be good for me to describe what happened to me with the same results/problems.I assume you are using the internal osc in the 'f629 so this is probably not applicable but I was running one with a HF xtal and I couldn't get it to program a second time.Realized once programmed,the thing was beating out the programmer and changing pin assignments that are used for the clock and data lines(this of course was ICSP).I wound up doing a 'see who wins' race by powering on right after I clicked 'program'.And voila(doesn't work every race but eventually...)Thought maybe this might help someone else that does a search for this problem.