See text below from the ST6 Windows Epromer 4.0.2 Release Note.
Make sure the NT parallel port driver is installed. This driver installs itself if not detected at the end of the windows epromer install. You should propably reinstall your windows eprommer software. --------------------------------------------------------------ST6 Windows Epromer can be installed on PCs and compatibles running with Windows ® 95, Windows ® 98, Windows ® 2000 or Windows ® NT ® 4.0 operating systems. Note: Installing WINDOWS EPROMER on a Windows ® NT or Windows ® 2000 machine for hardware programming tools which use the parallel port on your host PC, will trigger the installation of the NT Driver “STM Parallel Driver� if it has not yet been installed. In this case, administrator rights are required.