Well I just tested this out on a Win 2K SP4 machine and it doesn't have the REG command. I got the REG.exe out of the Windows 2000 resource kit and tried that, still no joy. Looks like the syntax on a 2k machine is reg UPDATE HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\'HideFileExt'=00000000 Still 10,000 thanks for pointing me in the right direction.