This seems to be an odd problem installing Nero v7.6.9.0 Lite. My entry for RunOnceEx looks like this : if exist "%DIR%\Nero7960_eng_lite.exe" ( REG ADD %KEY%\%NUM% /V 15 /D "%DIR%\Nero7960_eng_lite.exe /GROUP=\"DVD\\Nero 7\" /TASKS=\"!DesktopIcon\" /SILENT /LANG=\"English\" /COMPONENTS=\"Nero_Core,Nero_Core\\Nero_MauSau,Nero_Core\\Nero_VideoCD,nero_toolkit,Nero_CoverDesigner,Nero_WaveEditor\" /SERIAL=\"SerialSerialSerialSerialSerial\" /USER=\"Firstname Lastname\"" /f REG ADD %KEY%\%NUM% /V 16 /D "%DIR%\LS_HSI.exe /QB" /f ) %KEY% is set to HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnceEx %NUM% is set to 228 %DIR% is set to the source dir on the UACD - that's D:\APPS\DVDAPPS The install appears to start, but winds up creating a normal file in Program Files rather than an install dir, so the install silently fails. I can manually run the install from a CMD shell with D:\APPS\DVDAPPS\Nero7960_eng_lite.exe /GROUP=\"DVD\\Nero 7\" /TASKS=\"!DesktopIcon\" /SILENT /LANG=\"English\" /COMPONENTS=\"Nero_Core,Nero_Core\\Nero_MauSau,Nero_Core\\Nero_VideoCD,nero_toolkit,Nero_CoverDesigner,Nero_WaveEditor\" /SERIAL=\"SerialSerialSerialSerialSerial\" /USER=\"Firstname Lastname\" and it will install just fine. Well, I have to del the Nero file in Program Files first. I've also tested it with a clean setup, just running the install command above - works fine. So it seems to complain being run from RunOnceEx. Actually, being run from Run, RunOnce or RunOnceEx. Any ideas ? D. --edit - messed up definitions of variables above. Fixed.