They may be getting marked as junk. Try going to Tools>Options>Filters>Junk, and put a tick by one of the "Display Junk" options, then click apply.

Also make sure you have "All" selected in the columns to the left of your search results.

Also see: Fake files showing up in search results

How to find music (also tips for video)

Try the suggestions in this thread for blocking bad ip's: Problems with the search

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