My laptop did not come with a 9 pin serial port but I purchased the USB to serial port adapter from Radio Shack. The adapter came with a 3.5 inch disk. My laptop did not have a 3.5 inch disk drive so I downloaded the software from Radio Shack's website. When I installed the software the adapter was connected to the Tx. The adapter will now only work in one of my two USB ports (the one that it was connected to when I installed the software). USB now works on my laptop but only on one of the USB ports.

If you installed the adapter software correctly perhaps you should plug your adapter into a different USB port.

Hope this helps.

Ron