How To: Install a .msp file that is not recognized as a patch file
If a computer has an installed software product that uses the .msp extension, such as Paint Shop Pro, a patch file may not be recognized as a Microsoft Windows Installer Patch file and double-clicking on it will not start the install process.
Instructions provided describe how to call msiexec.exe directly, using the appropriate command line arguments and pointing to the .msp patch file through the following steps:
At a DOS command prompt, type 'msiexec.exe' to see if msiexec.exe can be found without specifying its full path.
If step 1 returns a message box from the Windows Install, proceed to step 3. If it is not found, search the computer for 'msiexec.exe',usually found in the system32 folder, and note the full path when found.
At a DOS command prompt use the following syntax to run the .msp file directly: C:>\<full path if required>\msiexec.exe /p <full path to the .msp>
In the syntax above, the /p is specified to incidate that a patch is being applied. Example: C:>\msiexec.exe /p C:\RevSP\PLTS30_Reviewer41_SP1.msp