It is not a good idea to download Programmes off Gnutella in my opinion. They often contain viruses, or they are incomplete or demo versions. It is a good idea to find out what size file you are expecting to find. If the search result doesn't match this .. certainly steer clear.
Software makers and Music companys do not like what some people get up to on Gnutella and put a lot of bad or infected files up.
Your music file, might just be a faulty file. A good file can turn bad for many reasons. Or it may be a deliberately planted bad one. Either way, you will come across them, but hopefully not too often.
I hope this helps
