I attempted to install Beta 4 whilst the indexer was running. During installation it said that files were in use and I'd need to restart the computer. After the restart (before running Logos) I got this error:

This was followed by a Windows Message saying the Logos4 Installer had stopped working.
Faulting application Logos4Setup.exe, version 4.0.3.4143, time stamp 0x4b216c4b, faulting module Logos4Setup.exe, version 4.0.3.4143, time stamp 0x4b216c4b, exception code 0x40000015, fault offset 0x0002010f, process id 0x4c4, application start time 0x01ca7a5dbf602e6f.