When I download mpg movie files in limewire 2.1 for mac os x, a very strange thing happens.

ex:

I download a 102mb mpg file. When I watch it in quicktime, or preview it in the finder, the duration of the file is incorrect. It says that the movie is only 35 seconds long... but I know it is longer. Limewire is downloading the entire file, but it somehow messes up the file so that applications read it as only a fraction of it's actual duration. I first thought that maybe this phenomena was file specific, but it has happened on a number of my movies. I don't think that it is a bug with the files, or with quicktime, because of this observation I made.

While a file was downloading, I checked the it's duration by previewing it from the "incomplete" folder. It read that the file was 6mb, and 1:47 seconds long. I closed the finder window, and went back into Limewire. After the progress bar for that file moved about another 25%, I checked the file in the finder again, this time it read 12mb, and 1:00 long. What is going on?!

I would really appreciate help with these two things:
a) a way to STOP this from happening
b) [only if possible] a way to salvage the 10 or so 100mb+ files I have on my HD that only play the first couple of seconds and then cut off.

Thanks.