Replace task manager using registry keys or api

Process Explorer has an option which I have used recently called "Replace Task Manager.". Now, every time CTRL + ALT + DEL is pressed on my system Process explorer comes up. However unfortunately despite what the documentation says the option does not change to "Restore Task Manager.".

I have looked for all instances of the taskmgr.exe located on my computer and despite them clearly being the original taskmgr.exe file - running any of them opens the system internals process explorer. If I delete the process explorer file and attempt to open task manager I get a file not found error.

So could someone please inform me is there a registry hack or API call (I assume registry hack) that I can make to resolve this issue?

Delete the reg key;

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\taskmgr.exe

Upgrade to the very latest version, 15.01, which appears to have fixed this bug.