I've tried installing Process Explorer 16.05 through the PortableApps launcher itself and as a PAF file from Sourceforge, and I always get an error message:
The downloaded copy of Process Explorer Portable (http://live.sysinternals.com/files/ProcessExplorer.zip) is not valid and cannot be installed. This could be due to an incomplete download or other network issue. Please try running the updater again when complete.
This is using a fresh install of PortableApps to my user profile folder on Windows 8.1 here on my work machine (in my case, C:\Users\Csmith).