I uninstalled Enderal, i uninstalled Skyrim from Steam, i deleted all remaining files in both the Steam Library dir (the ones from Tilliboy's rar & configs), i deleted everything from "My Games".
I redownloaded the torrent. I reinstalled Skyrim from Steam, i redownloaded the Launcher. I reinstalled Enderal. Still the same message (no SKSE found).
I'm not sure how this file calculates the MD5 sum, but it's what i found is preinstalled on Windows:
C:\Users\Fossi>CertUtil -hashfile G:\EnderalInstall_EN.gz MD5
MD5-Hash der Datei G:\EnderalInstall_EN.gz:
36 87 5c 4a 11 ba 74 8a 39 d9 c5 b9 9c c5 df 9d
CertUtil: -hashfile-Befehl wurde erfolgreich ausgeführt.
Maybe you can recalculate with that same tool.