Installing exe inside a JEA - Always Exit Code 2

Hi,

When attempting to install exe's using a JEA (WireShark and Notepad++ so far) the installers appear to be failing. PowerShell shows an ExitCode of 2 in both cases and tracking the process in ProcMon both results in pretty much the exact same thing!

Both installers fail when they attempt to write a file into C:\Windows\Temp with an Error of 5 (Access Code Violation)

The JEA itself is running as a Virtual Admin account
For troubleshooting purposes I have configured the JEA in FullLanguage Mode
For troubleshooting purposes I have configured the JEA to have access to all Providers (from Get-PSProvider)
MSI's work fine (and that's what is used the majority of the time)
I have also attempted to change the ACL on C:\Windows\Temp to give 'Everyone' R/W perms