[TYPO3-linux] Some thumbnails are not being generated in tt_news

[Juan Carlos Ceballos]

I have thumbnails enable on my site and it worked just perfectley but 
just this week I started getting in backend a partial generation of 
thumbnails in tt_news, I publish an image of the problem so you can have 
a good idea of the problem, you can find it here: 
http://img409.imageshack.us/my.php?image=thumbnailsttnews9qd.jpg

I'm running 3.7.0, I think it could be a permission problem, but I don't 
see how since it generates some thumbsnails, for the first 8 or 10 
pictures and after that it stops.