I only use VP occasionally, it's the best non-professional program -- but this issue now really keeps getting on my nerves: every now and then, I get a "hiccup" in transitions. When I manage to adjust them (playing with the timing or just deleting the transitions because the "hiccup" is still there, no matter what), then I find that one or more of the next transitions break in the same sequence!
I'm an organised person normally, so first I gather my video clips in separate folders, build up several sequences, then I link them into a final sequence.
I preview it before export, so when I find a broken transition and correct it, I need to re-watch the whole preview every single time to make sure the whole thing looks as intended. It's a neverending story.
Hiccup = the transition starts at the end of one clip, then proceeds to the next one but the clip suddenly stops, then jumps across several frames. Or, worse, there's a blackout instead of playing the transition.
PS. No, I'm not the one lame idiot who needs to link every single clip by transitions because he thinks it's "cool". The only ones I use here and there: crossfade, fade and fade to white.
And again, no, I don't just start any preview, I always wait for the thumbnails to buffer - that is why the whole thing takes ages, because every time you adjust ANYTHING, or load another tab etc., VP will re-buffer the clips and transitions in the sequence...)