Incorrect playback after editing

Having a following problem :
Writing a score for several instruments, playing some parts of the tune during the process. So when I, say, changed few notes in the bar - I want to play this bar afterwards to hear the result.. I'm highliting the first note of the bar, pushing space - and then one of 3 things happens pretty often :
- either it does not play it at all - only shows the "play" button in the tab active for a second - then it turns off
- either it starts the playback from some randomly picked part of the score - from the same one all the time
- or it starts playback from the very beginning of the score

Then I say few harsh words, stop the playback, highlight the same note again - and it pays it all from the correct place..
It happened all the time - whatever I would work on in MuseScore, on XP, Win7, does not matter...
That really pisses off)
Does anyone else have that problem? Maybe someone knows the way out?)