Have you tried rebuilding the search index.
You can do so by:
Clicking the start button and type:
Indexing OptionsInto the search box and press Enter.
In the
Index these locations pane, remove all the browsing history.
Now click the
Advanced button, and go to the
Index Settings tab.
Go to
Troubleshooting, and click on the "Rebuild" button, and see if the error is resolved.