When installing Kaspersky, half of the installation will fail to access the Windows Installer service, and the installation will fail. Solution: 1. Check whether the current user has administrator rights. As an internationally renowned security software, Kaspersky requires high level of system control, and low-privileged users cannot install software. 2. View the status of the Windows Installer service from “Control Panel - Administrative Tools - Services " or: Start-Run-Services.msc. If it is disabled, try to enable it, then re-install Kaspersky Test; 3. If it is found that it cannot be enabled, it is sometimes disabled by the system, or you can see the prompt: "The specified service has been marked as deleted", then go to Microsoft's official website to download the latest Windows Installer (WindowsInstaller-KB893803-v2- X86.exe) installer, try to reinstall the program. Before reinstalling, delete the three files msi.dll, msiexec.exe, msihnd.dll under the two folders %windir%system32 and %windir%system32Dllcache in safe mode. 4. If you encounter the prompt again, “The specified service already exists”, restart the computer to enter safe mode, then click “Start-Run” to enter CMD and stop msiexec/unregister from the command line window. This service, then run msiexec /regserver, then the service list will appear this item, double-click to adjust its status to automatic or manual start (there is a difference between the two, and adjusted to "automatic" after the need to restart). 5. Use the “Ctrl+Alt+Delete” shortcut or right-click on the taskbar to open the Task Manager, find and end the Ikernel.exe process in the process, and see if the Windows Installer installation and activation can be successfully completed. 6. If it still doesn't work, open my computer, find and delete the Windows Installer system installation directory from the system disk, and then enter the registry to delete the relevant information. 7. Use Notepad to write the installer.reg file as follows: Windows Registry Editor Version 5.00[HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\MSIServer]"ImagePath"=-"ImagePath"=hex(2):25,00, 53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,\\74,00,25,00,5c,00,53 ,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,6d,\\00,73,00,69,00,65, 00,78,00,65,00,63,00,2e,00,65,00,78,00,65,00,20,00,2f,00,\\56,00,00,00 then save the file For the ”.reg“ format, double-click the file to import the contents of the file into the registry. Step 2: Restart the computer to enter safe mode (press F8 when starting), then click ”Start-->Run“, enter ”CMD“ command, pop-up "CMD command prompt“ window Enter ”msiexec /regserver“, and finally restart the system. 8. Download and install the Windows Installer CleanUp Utility 1.0 provided by Microsoft. Its main function is to clear the Windows Installer configuration information of the program. After launching the tool, select Kaspersky and click the “Remove” button. 9. Let the system repair itself, using the sfc/scannow command that comes with Windows. The ultimate solution to recover the system.