How do you know they are not fakes? Fakes will show up as the right size, right name, etc. But usually show up in very high numbers. As I just explained here http://www.gnutellaforums.com/showthread.php?t=61247

To test to see if the problem is your school, try an experiment by downloading a magnet link from here http://www.magnetmix.com/video.shtml
If successful then those files you earlier selected were probably fakes.