Hi Robert,
As I am totally unfamiliar with the MELabs programmer, this will be a W. A. G. so be kind, please.
My idea concerns the config fuses. Are they set in your code, or do you set them manually in the programmer?
Is there a possibility of an incorrect OSC. choice or MCLR set wrongly . . . ? Pretty much what WDMAGIC said huh? DOH !