Vertical white bar(s) on screen after connecting my 2300 MP to a laptop

When I connect my laptop to my 2300 MP beamer vertical white bars appear on the screen. They may disappear for a whie, than flickering starts and the vertical white bars are back again. Sometimes it is one bar, sometimes tw whiyte bars

When the projector is on without being connected to a laptop or desktop there are no white vertical bars.

I have tried a factory reset and changed the bulp, both did not help at all.

Please help.