OK, good news is that running MSI files directly does work... bad news is, when that MSI has a dependency (usually a DATA1.CAB file), it gives the following Windows Installer Error: "This installation package could not be opened. Verify that the package exists and that you can access it, or contact the application vendor to verify that this is a valid Windows Installer package" When I double click the same MSI file in windows explorer, it runs fine. My guess would be something to do with the setting for the current directory reported to Windows Installer - perhaps it's getting changed to something else after the MSI is called? EDIT: I did some investigation, and found that if the MSI has dependencies, they can't be found because the path contains an invalid character - the "/" used in the HTML to point to where the MSI is. This prevents the correct directory from being set. Is there any way to get around this? *2nd EDIT* fixed with "\\" in place of "/" Also, is the "bass.dll" required even if music playing isn't required? I have the "BassEngine=Off" entry in my menu.ini, but the Autorun won't seem to function without it. Any way to remove the dependency on the "Bass.DLL" file? I don't (and won't in the future) have a need for it Thanks