Ok, there can be a number of reasons for your search to break, but due to a number of recent situations and patches, here’s a new one cropping up quite a bit lately. I’m outlining the symptoms I ran into tonight (your situation may differ).

The Issue

Search is busted. All of a sudden, nothing obvious about it. No usable errors besides all of a sudden, a perfectly functioning search dies and you get…

No results matching your search were found.

1. Check your spelling. Are the words in your query spelled correctly?
2. Try using synonyms. Maybe what you’re looking for uses slightly different words.
3. Make your search more general. Try more general terms in place of specific ones.
4. Try your search in a different scope. Different scopes can have different results.

The fix (or one of them)

Read: http://support.microsoft.com/kb/896861

Note: Option #1 is the recommended course of action as it is more secure.

This fix also applies to recent 401 errors and appears to be becoming more wide spread.Note: Spence Harbar has a great blog post detailing *why* this occurs and also when you should, and shouldn’t take tihs approach.  Read it here.