Version 1.00 is either the first version that should be replaced by the forced upgrade of Steam, or an illegal version.
Version 1.00 was sometimes used illegally because it had no steam restriction.
Enderal and SKSE are not compatible with it. You need a legal skyrim.
If your Skyrim runs legally on Steam, you probably need to do a clean reinstall.
An error occurred during the update or was never executed.
Or your steam is broken.
Repairing Skyrim will not help, as it destroys Enderal.
Uninstall Enderal, uninstall Skyrim, and then delete the following folders:
D: \ Steam \ SteamApps \ common \ Skyrim \
"% USERPROFILE% \ Documents \ My Games \ skyrim"
"% USERPROFILE% \ AppData \ Local \ skyrim"
Then re-install Skyrim, update via Steam, start short, do not save.
(Test run Skyrim)
Then install Enderal as described, update, start the game.
(Test run Enderal)
Set settings and have fun with Enderal.