No, WINQSL runs without any problem under all currently available MS-environments. There was only a very limited number of CD´s which had a problem with Windows NT and if you use the same CD now under XP there appears a problem. Those CDs start with the serial-number 01XX and are more than six years old. So if you have one of those CDs just drop me a line. All CDs with 02XX and higher work without any problem.