I am experiencing this problem on both Macs and PCs.
In Powerpoint 4.0 and 95 although I appear to have timed transitions on slides when viewed in the slide sorter, when the presentation runs the slides don't change after the allocated time. They will only change on a mouse click or keyboard action.
Powwerpoint 3 works perfectly well in this regard.
I can't find any clues in the online help.
Any suggestions welcome