Notes not showing in slide show

Impress 4.4.3.2 (also 4.4.1) English
Windows 7 extended desktop (Built-in + Monitor) XVGA English
Notes show and are editable with the slides in the Notes view, but the notes window is blank for all slides in the slide Show.
The file is saved as a .PPT, but saving it as a .ODP makes no difference.
Turning off and on again the Notes display in Slide Show does not help.
It worked yesterday, but today nothing. Even upgrading to 4.4.3.2 will not get the notes to show.
The notes are also not recognized if I open the file in MS Powerpoint 2007.
Help!