I am having 2 computers right now having this same error code. Getting frustrated and do not want to have to reformatt the machines to fix it.
Things i have tried:
-Microsoft Fix it 50535 (Manual MSE uninstaller)
-msremoval.bat (Script to get rid of MSE)
-msicuu2.exe (Windows Installer Clean up Utility)
-along with various other things in the registry , deleting mse keys.
I also attempted to copy paste the source it gives me into the registry and delete that specific entry, but gives me the same problem when i attempt to reinstall.

I managed to get it to show that there are no other antivirus programs installed in the security center.

Pics below of whats happening.




Any other ideas would be greatly appreciated..