I have a VS2008 clickonce application with a custom prerequiste, which I install with the bootstrapper. When deployed online, the prerequisite is downloaded and installed fine. No problems. When deployed via CD to a Windows XP machine, also fine as above. No problems. However, when deployed via CD to a Windows 7 machine: the prerequisite is downloaded - good then the user is asked for permission to the run the file - good then the installation of the prerequiste is just SKIPPED - bad and the ClickOnce application installation begins without the prerequisite - bad Has anyone encountered this weird behaviour? I cannot find a solution anywhere.