Mght not be an actual 'Fix' as I have never heard of this happening before, but go into Settings.app, go to General and then to Spotlight Search (SETTINGS >> GENERAL >> SPOTLIGHT SEARCH) and have a look at the order and what is selected to be searchable. Make sure everything you want on is on and make sure they are ordered how you want?
Also, are you jailbroken? I assume you haven't got any tweaks installed which hook into spotlight search screen?