In Windows Vista, it is quite possible that your search index may become corrupt or unusable. In a situation like this, it is fairly easy to rebuild the search index in Windows Vista.
Click the and type indexing (Figure A).
Next, select Indexing Options from Instant Search (Figure B) and click Advanced and select Rebuild to rebuild the index from scratch (Figure C).
You also have the option of creating a new location for the index as well as indexing encrypted files.
Do yourself a favor and grab a cup of Joe or some Tea? This is going to take awhile.