Windows 8 - autorepair (endless) loop

Hi

I have a Dell XPS 2720, running Windows 8.1

Since Monday morning the computer is unusable... 

when turning on it shows "Preparing automati repair" ... and keeps like that for hours.

Power Off, then On again does not change anything.

I did the Dell ePSA diagnostics, no errors found.

Tried to reach Windows Troubleshoot menu, as suggested here: "en.community.dell.com/.../19524794" but could not bring up that menu.

Please help.