Error code 12150

[chartman]

I am trying to upgrade from 7.5.3 Plesk for Windows to 7.5.6 so I can do an upgrade to 8.1.

I am getting a "Unknown error {Error code 12150} at HttpQueryInfo{http://download1.swsoft.com/Plesk/Plesk7.5/Windows/7.5.6/051107.20/MailEnableStandard.exe"

Any ideas about what this is trying to do?

For an "unknown" error it seems to have some real specifics that it "knows" about.

Thanks