AccelePort 8P problems

I am running a serial interface on a acceleport 8p card installed on a windows 200 server that sends then receives 32 bytes of data every 5 seconds. After 10 to 24 hours the program begins to build up on overruns and locks up the computer. The problems seems to be with the COM port. Is there any settings on the port or ideas as what sould be causing this?

Kevin Wood
US Steel