I am running embedded XP on a Pentium Windows computer. After moving from Windows 98 to XP all serial comm from the serial port fails. WriteFile sets the correct number of characters written, but no output. I can remotely debug my program on the pentium machine with my PC, and WriteFile reports the correct number of chracters send, but nothing comes from the serial port. I have tried a NULL modem cable and a straight cable connection while running hyper-terminal on both machines with no luck at all. What are the issues in migrating serial comm from Windows 98 to XP? What do you think I should try to fix my problem? After 2 days I'm out of guesses.