Experiencing this?
When you try to install/uninstall some application/s, you may get warning messages like:
"The Windows Installer Service could not be accessed"
"Windows Installer Service couldn’t be started"
"Could not start the Windows Installer service on Local Computer. Error 5: Access is denied."
http://www.support.microsoft.com/default.aspx?scid=kb;en-us;555175&SD=tech