It maybe caused by fake files:
Fake files showing up in search results
Try the suggestions in this thread:
Problems with the search
Also see:
How to find music(and videos)
Are you fully connected to the network? Do you have green or blue connection bars in the lower left corner? Do you see a brickwall in front of the globe icon?
Could you supply your details?
System details - help us to help you -> Provide these details when you post!!!