O.K cool. As you say you're a newbie so here's a few explanation.

The great FLASH-LAB 77 you buy from Reynolds give you all you need to program/debug your program within MicroCode studio Loader. If you don't include this DISABLE DEBUG line, PIC16F877 will try to communicate with MicroCode Studio at his boot time. Since you're "offline" when you disconnect the serial cable, the PIC16F877 is waiting for MicroCode studio command. That's it.

happy to help you

a la prochaine