The Windows Installer Service Could Not Be Accessed

"The Windows Installer Service Could Not Be Accessed" error when you try to install a program in Windows 7 or Windows Vista

To do this, follow these steps:

1. Click Start, and then type Notepad in the Search box.
2. Under the Programs heading, click Notepad.exe.
3. Copy the following text, and then paste it into a notepad: 
   
   

   Windows Registry Editor Version 5.00
    
   [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\msiserver]
   "DisplayName"="@%SystemRoot%\\system32\\msimsg.dll,-27"
   "ImagePath"=hex(2):25,00,73,00,79,00,73,00,74,00,65,00,6d,00,72,00,6f,00,6f,00,\
     74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,6d,\
     00,73,00,69,00,65,00,78,00,65,00,63,00,20,00,2f,00,56,00,00,00
   "Description"="@%SystemRoot%\\system32\\msimsg.dll,-32"
   "ObjectName"="LocalSystem"
   "ErrorControl"=dword:00000001
   "Start"=dword:00000003
   "Type"=dword:00000010
   "DependOnService"=hex(7):72,00,70,00,63,00,73,00,73,00,00,00,00,00
   "ServiceSidType"=dword:00000001
   "RequiredPrivileges"=hex(7):53,00,65,00,54,00,63,00,62,00,50,00,72,00,69,00,76,\
     00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,43,00,72,00,65,00,61,00,\
     74,00,65,00,50,00,61,00,67,00,65,00,66,00,69,00,6c,00,65,00,50,00,72,00,69,\
     00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,4c,00,6f,00,63,00,\
     6b,00,4d,00,65,00,6d,00,6f,00,72,00,79,00,50,00,72,00,69,00,76,00,69,00,6c,\
     00,65,00,67,00,65,00,00,00,53,00,65,00,49,00,6e,00,63,00,72,00,65,00,61,00,\
     73,00,65,00,42,00,61,00,73,00,65,00,50,00,72,00,69,00,6f,00,72,00,69,00,74,\
     00,79,00,50,00,72,00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,\
     65,00,43,00,72,00,65,00,61,00,74,00,65,00,50,00,65,00,72,00,6d,00,61,00,6e,\
     00,65,00,6e,00,74,00,50,00,72,00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,\
     00,00,53,00,65,00,41,00,75,00,64,00,69,00,74,00,50,00,72,00,69,00,76,00,69,\
     00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,53,00,65,00,63,00,75,00,72,00,\
     69,00,74,00,79,00,50,00,72,00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,00,\
     00,53,00,65,00,43,00,68,00,61,00,6e,00,67,00,65,00,4e,00,6f,00,74,00,69,00,\
     66,00,79,00,50,00,72,00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,53,\
     00,65,00,50,00,72,00,6f,00,66,00,69,00,6c,00,65,00,53,00,69,00,6e,00,67,00,\
     6c,00,65,00,50,00,72,00,6f,00,63,00,65,00,73,00,73,00,50,00,72,00,69,00,76,\
     00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,49,00,6d,00,70,00,65,00,\
     72,00,73,00,6f,00,6e,00,61,00,74,00,65,00,50,00,72,00,69,00,76,00,69,00,6c,\
     00,65,00,67,00,65,00,00,00,53,00,65,00,43,00,72,00,65,00,61,00,74,00,65,00,\
     47,00,6c,00,6f,00,62,00,61,00,6c,00,50,00,72,00,69,00,76,00,69,00,6c,00,65,\
     00,67,00,65,00,00,00,53,00,65,00,41,00,73,00,73,00,69,00,67,00,6e,00,50,00,\
     72,00,69,00,6d,00,61,00,72,00,79,00,54,00,6f,00,6b,00,65,00,6e,00,50,00,72,\
     00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,52,00,65,00,\
     73,00,74,00,6f,00,72,00,65,00,50,00,72,00,69,00,76,00,69,00,6c,00,65,00,67,\
     00,65,00,00,00,53,00,65,00,49,00,6e,00,63,00,72,00,65,00,61,00,73,00,65,00,\
     51,00,75,00,6f,00,74,00,61,00,50,00,72,00,69,00,76,00,69,00,6c,00,65,00,67,\
     00,65,00,00,00,53,00,65,00,53,00,68,00,75,00,74,00,64,00,6f,00,77,00,6e,00,\
     50,00,72,00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,54,\
     00,61,00,6b,00,65,00,4f,00,77,00,6e,00,65,00,72,00,73,00,68,00,69,00,70,00,\
     50,00,72,00,69,00,76,00,69,00,6c,00,65,00,67,00,65,00,00,00,53,00,65,00,4c,\
     00,6f,00,61,00,64,00,44,00,72,00,69,00,76,00,65,00,72,00,50,00,72,00,69,00,\
     76,00,69,00,6c,00,65,00,67,00,65,00,00,00,00,00
   "FailureActions"=hex:84,03,00,00,00,00,00,00,00,00,00,00,03,00,00,00,14,00,00,\
     00,01,00,00,00,c0,d4,01,00,01,00,00,00,e0,93,04,00,00,00,00,00,00,00,00,00
    
   [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\msiserver\Enum]
   "0"="Root\\LEGACY_MSISERVER\\0000"
   "Count"=dword:00000001
   "NextInstance"=dword:00000001

4. Click File, click Save As, and then name the file Msirepair.reg.
5. In the Save as type box, click All Files (*.*).
6. In the Save in box, click Desktop, and then click Save.
7. On the File menu, click Exit to close notepad.
8. On the Desktop, right-click Msirepair.reg, and then click Run as administrator. If you are prompted to enter an administrator password or provide confirmation, type the password, or click Continue.
9. Click Yes when you are prompted to install the registry keys.
10. Restart the installation process for the program that you want to install.