I have used many of the cheap usb/serial cables without problems and have found the bigest problems come from the wrong drivers and not the cables, as every one tends to blame. (operator error not hardware problem)
The first problem starts with windows trying to load a driver with the wizard........close the wizard first, before installing the 3rd party driver.
Once a wrong driver is installed it will prevent the correct driver being installed, you will need to delete the wrong driver from the driver software you installed it with.
If you can post a photo of the cable i might be able to help.
If its has green plugs with silver cable then it is made by Ritmo, and the driver is on their web site but hard to find, often these cables are sold with no name and no driver.
If this sounds like your cable then i can give you the correct driver.
Pete.