Movie Maker sound track shift

A recent movie I tried to edit (about 40 minutes long)
has several problems with sound:
- sound tracks keep lagging the video (it plays fine in
clip-by-clip mode)
- If I added a sound effect in many cases final movie does
not have the original sound of video clip (it also plays
fine in clip-by-clip in most of cases; occasionally, I
need to press "Reset" sound to hear it). Finally, I had to
switched to ArcSoft ShowBiz.
Any idea?
Thanks
Alex