These days reload the computer, encounter a series of error information about Windows Installer, check some relevant information on the Internet, finally solved. Question 1: 1. All the programs installed using the installer cannot be installed. Tip: "You cannot access Windows Installer service. Maybe you run Windows in security mode, or Windows Installer does not have the correct installation. Please contact your support to get help" Second, check Windows Installer service, generally deactivation. If you try to enable it in Service, it is sometimes discovered that it is disabled, then launched, prompt: "The specified service is marked as delete". The MSI Installer can be a real pain. It may be that one of the files required by it is corrupt. Here's what you do. Run msiexec / unregserver again. Then delete msiexec.exe from the system32 directory. Potentially, you could rerun the install at this point but for some reason this does not always work. Instead, download a fresh copy of the windows installer, use an unzipping tool to extract it, go into the folder and manually install from the inf files. to do this, right click on it and select install. Make sure you do msi.inf first, and then mspatcha.inf or you get a missing file error (likely because msiexec.exe is missing). After all this run msiexec.exe / regserver to recreate One, first stop Windows Installer service with MSIExec / Unreg Server. Second, download INSTMSIW.EXE, unzip it with WinRAR. Enter the directory. Third, right-click msi.inf, click the installation, right-click Mspatcha.inf, click Install. Fourth, use MSIExec.exe / RegServer to enable service. Question 2: After the above problem is solved, when I installed the VPC, I met this question: Error -1607: Unable to install installshield scripting run time After checking the relevant information, I found that there is no Isscript.exe installed in the system. So I downloaded and updated the Ikernelupdate.exe and Isscript7x.zip ... The problem was solved. Of course, many times the reason is not necessarily the same, and the solution is not necessarily the same, I just take my solution, it is a reference.