Sounds like you're trying to download a fake file. They're common now.
Search again, vary your search terms, try the All Types search. Stay right away from files with lots of sources, go for a file with 10 sources or less, or those with a modem source.

For movies, always check a file before download with Bitzi. A file with heaps of sources but no Bitzi rating is often a fake.
How to use Bitzi

For music, try the tips in this thread
How to find music

And for some general info about these fakes
Info about fake files