We were experiencing a problem where the Master Synchronous Serial Port (built in peripheral for our backplane SPI comms) seemed to be giving up on transmit, as soon as the program counter crossed into 0x100. It turned out to be a faulty computed-GOTO routine, which had a blind spot for the carry flag! Best wishes, Matt Rhys-Roberts -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist