I have found out that "blank screen" isn't neccesary blank - actually it is a freezed screen.
Eg. playing a video on youtube in FF then the picture freezes except the mouse. I can pause/start the video - but can't see it.
Normally the screen is only "blank" on the GUI (Ctrl-Alt-F7) - but I have one time observed that switching to a TTY (Ctrl-Alt-F2) (without loging in - so I see the text login prompt) and back to GUI then I see the same text + mouse.
I will commit log files when I see the problem again.
I have found out that "blank screen" isn't neccesary blank - actually it is a freezed screen.
Eg. playing a video on youtube in FF then the picture freezes except the mouse. I can pause/start the video - but can't see it.
Normally the screen is only "blank" on the GUI (Ctrl-Alt-F7) - but I have one time observed that switching to a TTY (Ctrl-Alt-F2) (without loging in - so I see the text login prompt) and back to GUI then I see the same text + mouse.
I will commit log files when I see the problem again.