Windows 7 x64 won't install MSI packages

[Dave]

A friend of mine and I wanted to play some games and stuff online, so I suggested installing Hamachi and Steam. However, his computer throws an error up when he tries to run any MSI package.

This installation package could not be opened. Verify that the package exists and that you can access it, or contact the application vendor to verify that this is a valid Windows Installer package.

Link to image of similar error.

The error has a slightly different look to it than most error messages I've seen, which makes me wonder if it's not some malware preventing installations. Again, he's running Windows 7 64-bit, fairly recent install.

I've looked around online, but nothing looked promising. He was running Avast Antivirus, and I suggested MSE, Spybot S&D and MalwareBytes, but otherwise I'm not sure where to start on this issue.

[Executor32]

Run services.msc and ensure that the Windows Installer service is running, that should fix it.