I was trying to install the .Net Pet Shop 4.0 on Windows Vista and kept getting the error:  The source was not found, but some or all event logs could not be searched.  Inaccessible logs: Security.  There is no right click option, Run as administrator for .msi files.  You can, however, run the CMD prompt as Admin, then the following:

    msiexec  /a "Microsoft .NET Pet Shop 4.0.msi"

Another useful command to crack open a .msi installer file:

    msiexec /a "Microsoft .NET Pet Shop 4.0.msi" /qb TARGETDIR=c:\temp

It might also help to do a:

runas /user:domain\user msiexec /a "Microsoft .NET Pet Shop 4.0.msi"

easier method is run cmd.exe as administrator and then launch .msi file