First, with the LocoBuffer-USB plugged into the machine see
if there are 'LocoBuffer-USB' entries under the hardware
device listings for "Ports (Com & LPT)" and/or "USB
controllers" If so, uninstall them. Now unplug the
LocoBuffer-USB from your computer and plug it in again. This
should allow you to re-install your drivers.
Windows users should also go into the Control Panel. Choose
"Add or Remove Programs. This will open up a window listing
all the programs on your machine. Look for one with "FTDI"
name. For example it might be "FTDI USB Serial Converter
Drivers". Select it and remove it if possible.
For more install help go to
Windows XP Driver installation.