Notebook screen blanks when cover fully open

Hello,

I have a weird problem. Whenever i open the cover at startup Windows blanks the notebookscreen.
If i attach a second monitor i can see iWindows has started succesfully.

If i just lift the cover a little bit (a few cm) and then power up Windows starts on the notebookscreen.

Anyone an idea?

Its a HP Pavillion DV9790ed.

Kind regards,
Marcel