Hi, this thread helped me thanks, because I was connected to a screen through DVI, using an HDMI to DVI convertor. I had to go into the mentioned config.txt on the boot partition and changed the HDdrive setting from HDMI to DVI. This solved it for me.
It worked straight strangely enough when I was using a vga screen with VGA to HDMI convertor. It seems that connecting via DVI does not trigger the autodetection in the boot config.