A8N-SLI-serial port erratic

For some reason the one serial port on this board behaves erratically. I only have one
application requiring that port. At times after a restart, that program (a weather
station) reports that it cannot contact the sensors which report via the rs232 port.

Sandra pro shows that port active, but not for the proper app. I sometimes have to
restart two or three times before it will work properly.

On this board, the port is connected via a cable from the board to an external connector,
not a direct connection.

My question, could the cable be bad, or the cable from the mb to the external connector?

BTW, I tried to use the many USB 2.0 connectors but the one USB to Serial connector did
not connect properly and the data was often delayed.

Any suggestions?

Thanks,