incorrect length of clips


I am experiencing the following strange problem. I import video clips which I have recorded with my digital camera (a Casio Exilim). When I then place them in the editing pane and play them I notice that the ruler (the vertical line that moves, sorry for not knowing the correct name) doesn't correctly identify the position in the clip. It will reach the end of the clip on the pane, but the movie will still play for a few seconds.

It gets worse when I concatenate clips. Although transitions, etc. are applied correctly the ruler position is completelly off-sync with the actual position on the clip. The ruler always gets to the end of the movie before it has actually finished playing and will stay in that position (the movie correctly plays until the end).

Apart from making it very difficult to actually edit there is a far worse effect that happens when exporting the timeline. The export will terminate when the ruler reaches the (supposed) end of the clip, effectively truncating the movie.

Somehow the individual clip lengths seem to be calculated incorrectly. If anybody could point me to a possible solution to this problem I would be very grateful.