I recently reinstalled Windows. Portable Apps shaved off a ton of time during the reinstallation process. It is awesome to return to the DOS days of computing on the modern desktop where each application is self-contained as all applications should be.
However, during my reinstall, running the Portable Apps updater at first resulted in the message, "The downloaded copy of ... is not valid and can not be installed. This could be due to an incomplete download or other network issue. Please try running the updater again when complete." Re-running the updater resulted in the same message. There's something about repeating the same thing again and sanity that could be said here.
I eventually resolved the problem after I realized that I hadn't run Internet Explorer before. So I ran IE for the first time, got through all of the dialog boxes and then shut IE down. After that, the Portable Apps updater worked great. I've always half-figured that IWebBrowser2 was behind the scenes of the updater, which is unfortunately susceptible to IE's weird initialization quirks. Not really a Portable Apps problem but the error message could be adjusted a little bit.