Slide-show freezes when I try to run the show in manual mode

When I switch on the slide-show modus = manual I get the message
"Manual mode does not support these settings".
The maximum show-time in automatic-mode is 20s, which is sometimes not sufficient to talk about the pic with friends, hence I'd like to run the slides in manual mode.
When I search in Google for this issue I get hints, that I should switch off music etc., but I have no music-file attached. Another hint says that this message is an system-issue and can be ignored, it should run anyway: which is not true. The show runs for e.g. ten pics, then it freezes and stops.