I received a few errors after modifying my search criteria to include almost all files on the C drive. There are more than a few file extensions that are not included in searchable "file types". I added these manually by determining which ones were missing by looking at each event log entry. For example, "QFN" was not in the list. I added this file type and that particular error went away.
You may not have these errors if you did not "customize" your indexing to include more items than the default.
Here is the procedure to custom add additional file types:
1. From Control Panel, open Indexing Options.
2. Click the Advanced button.
3. On the File Types tab, verify whether the file type you want is listed and selected.
4. If it is listed but not selected, select the file extensionís check box.
5. If it is not listed, enter the file extension in the text box at the bottom of the dialog and click the Add new extension button.