Repairing the Windows Installer Service

Repairing the Windows Installer Service
For a variety of reasons, the Windows Installer Service can at times fail. This typically becomes apparent when one is unable to add or remove an application and receives an error like, "Error 1719" The Windows Installer service could not be accessed."
The following fix is a simplified version of the steps listed on Microsoft's Knowledge Base:http://support.microsoft.com/kb/315346
DO NOT follow these instructions as they do not prepare you for service re-install.
Method 1
Confirm the presence of the installer service.
click Start, and then click on Search
click All files and folders
in the File name box, type msiexec.exe, and then click Searchthe location of the file should be %WINDIR%\System32 where %WINDIR% is your Windows directory
Confirm the registry enrty for the installer service.
click Start, and then click Run
in the Open box, type regedit, and then click OK
navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSIServer
make sure the entry for ImagePath is "C:\WINDOWS\system32\msiexec.exe /V"if it does not reflect the location of msiexec, make sure that it does
Register msiexec.exe
Reboot your workstaion and Press F8 to enter Safe Mode
Once in Safe Mode, click Start, and then click Run
type the following line, and then click OK:msiexec /regserver
Shutdown and restart your PC
if you still receive the error message follow steps in Method 2.
Method 2
Re-install the Windows Installer by first disabling the backup in DLLCACHE (not System32)
click Start, and then click Run
in the Open box, type cmd, and then click OK
at the command prompt type:
attrib -r -s -h "%Windir%\system32\dllcache"
this remove the Read Only, System and Hidden flags
At the command prompt, change directory by typing:
cd %WINDIR%\system32\dllcache
now type the following lines, pressing ENTER after each line:
ren msi.dll msi.old
ren msiexec.exe msiexec.old
ren msihnd.dll msihnd.old
this renames and thus disables the Installer Service backup files
Shutdown and restart your PC
update the Windows Installer files to the latest release