*** Didn't see the last posts - glad you got it sorted ******
Have you checked to make sure that there is nothing strange in you item descriptions? Someone had flaky search results because they had pasted from an Excel spreadsheet.
Other than strange stuff in the database, the only thing you can do is go back to original files until you find which one is causing the problem. It will be much easier to diagnose after you find the right page to work with. Since you say you didn't add any pages, it shouldn't take that long. Don't forget to backup. :)