I'm in a situation where I need to install an msi before my application if it is being installed on Vista. I've tried creating a custom action to detect and install but got an error saying that an installation was already in progress (the parent install). I've tried putting an old macromedia director exe in front but it is having compatibility issue with vista. I had toyed with the idea of creating a seperate exe that would kick off the correct installer but as this happens before my app installs I can't be sure that .net frmwrk 1.1 is installed. Can anyone suggest a solution?