Given the number of users you have, I have no idea why I'm almost the only person asking questions in English, but here comes another one:
I just uploaded a little trail and clicked 'Compute' to update the statistics. This gave a time of 121 minutes. I then printed out the same trail and got a time of 2h24mins, which is 144 minutes (isn't it?). The second time was correct, as far as I can see. To confirm, I downloaded the .gpx file, and the first recorded time is
and the last is
Which makes the time difference 2h24I believe. Accordingly I was able to update the computed statistics by hand; but since the data was there, why was the computation wrong?