First, be sure you have installed the drivers on the disk that came with the cable. I know windows installs drivers automatically, but often these do not work correctly. I would recommend loading the ones from the disk.

If it still gives you trouble, you may need to reassign a comport on your computer. For this, follow the instructions below. It has helped many people and is pretty easy to do.

COM PORT REASSIGN

1. Go to Control Panel, the click on System
2. Select the Hardware Tab, then press the Device Manager button
3. Scroll down until you find the Ports (COM & LPT) option and click it.

If your adapter is plugged in, find the one that says "USB to Serial" be sure it is on port 1,2,3 or 4. If it is 5 or higher we have to reassign it. Double click on the "USB to Serial"

4. Select the Port Settings tab. Click on Advanced. It should open a window
titled "advanced settings for COM1

5. In the bottom left corner of the screen it says "COM Port Number". Click here.

There will be several options. Some of them will say in use. DO NOT MESS WITH THESE!
Look for COM1, COM2, COM3 or COM 4. Select any one of these 4 that do not say "in use".

6. Click OK to all of the windows until you get back to the device manager screen.

Close the device manager screen to get back to your desk top.

The COM PORT has been reassigned and you should be able to use the converter cable with that usb port.

Be sure that the com port on the loader window is the same as the number you selected earlier when you load a file.