USB converter Cable Problem

I have a handheld two-way radio which is programmed via a proprietary
software application. I have the software installed on two computers, a
desktop and a laptop. The laptop is a Dell running XP Home (SP2) and
the desktop is a new custom build running XP Pro. I am trying to
connect to the radio with a USB to serial converter cable. The USB
converter cable was supplied by the radio manufacturer (Bendix/King).
With the desktop I put in the driver CD and I plugged the converter
cable into the desktop, XP "found new hardware" and installed several
drivers. The software on the desktop "recognizes" the radio and
exchanges data between the software and the radio perfectly. If I look
at device manager as I plug the converter cable into the desk top, XP
adds a new icon under USB controllers labeled "USB serial converter" and
another icon under Ports (COM & LPT) which is labeled "USB serial port
(COM X)" where X is the port number.

I followed the same installation sequence with the laptop, however XP
appeared to only install one driver and never gave me a "found new
hardware" pop-up. The software cannot "find" the radio. I have
uninstalled and reinstalled the driver several times w/ no change. A
new USB device shows in device manager under the USB Controllers, but it
is not the same as the one on the desktop and it is present all the
time, and there is no "USB serial port" under Ports. I suspect that
there are some old drivers on the laptop from previous versions of
"Street Atlas" and /or "Palm Desktop" which both used a USB to serial
converter at one time, and these old drivers are preventing the
installation of the newer drivers for the radio software. Anyone out
there have any idea what I have to do to locate and get rid of the old
drivers so I can get the correct drivers installed on the laptop?

Gary