If you are having problems searching in Vista -- files not being found, searches taking a *really* long time, etc -- either in the file system search, or the search built into Outlook 2007, it's possible that the search index has been corrupted. If this happens, the easiest way to fix the problem is to rebuild the Vista search index.

To do this go to the Start menu, type indexing and then launch Indexing Options when it comes up in the results. Once the Indexing Options panel is shown, select the Advanced button and then the button labeled Rebuild. Rebuilding the search index in Vista is a fairly long process, so it's a good idea to do this before you go to bed or stop using your computer for the evening so that it can chug away at the indexing while you are not using the computer.