After reindexing a site with about 800 file attachments (using Tika as text extraction agent BTW).
Can see that tables are populated with sensible search indexing data.

On performing an Attachments search on any term I get this error message (and no hits):

user warning: BIGINT UNSIGNED value is out of range in '(`database`.`f`.`timestamp` - 1276209749)' query: SELECT COUNT(*) FROM (SELECT i.type, i.sid, 5 * (7.51822413201 * SUM(i.score * t.count)) + (5 * POW(2, (f.timestamp) - 1276209749) * 6.43e-8) AS score FROM search_index i INNER JOIN search_total t ON i.word = t.word INNER JOIN files f ON f.fid = i.sid INNER JOIN upload u ON u.fid = f.fid INNER JOIN node n ON n.vid = u.vid INNER JOIN node_access na ON na.nid = n.nid WHERE f.status = 1 AND (na.grant_view >= 1 AND ((na.gid = 0 AND na.realm = 'all') OR (na.gid = 1 AND na.realm = 'book_access') OR (na.gid = 0 AND na.realm = 'content_access_author') OR (na.gid = 1 AND na.realm = 'content_access_rid') OR (na.gid = 1 AND na.realm = 'term_access'))) AND (n.language ='en' OR n.language ='' OR n.language IS NULL) AND (i.word = 'farnborough') AND i.type = 'search_files_att' GROUP BY i.type, i.sid HAVING COUNT(*) >= 1) n1 in /Library/WebServer/Drupal/drupal-6.22/modules/search/search.module on line 957.
user warning: BIGINT UNSIGNED value is out of range in '(`database`.`f`.`timestamp` - 1276209749)' query: SELECT i.type, i.sid, 5 * (7.51822413201 * SUM(i.score * t.count)) + (5 * POW(2, (f.timestamp) - 1276209749) * 6.43e-8) AS score FROM search_index i INNER JOIN search_total t ON i.word = t.word INNER JOIN files f ON f.fid = i.sid INNER JOIN upload u ON u.fid = f.fid INNER JOIN node n ON n.vid = u.vid INNER JOIN node_access na ON na.nid = n.nid WHERE f.status = 1 AND (na.grant_view >= 1 AND ((na.gid = 0 AND na.realm = 'all') OR (na.gid = 1 AND na.realm = 'book_access') OR (na.gid = 0 AND na.realm = 'content_access_author') OR (na.gid = 1 AND na.realm = 'content_access_rid') OR (na.gid = 1 AND na.realm = 'term_access'))) AND (n.language ='en' OR n.language ='' OR n.language IS NULL) AND (i.word = 'farnborough') AND i.type = 'search_files_att' GROUP BY i.type, i.sid HAVING COUNT(*) >= 1 ORDER BY score DESC LIMIT 0, 10 in /Library/WebServer/Drupal/drupal-6.22/modules/search/search.module on line 957.

To get a feel for the size of the indexed content, an SQL dump is about 100M larger than before the Search Files indexing.

BTW even without full indexing, and before I get this error above, I am not getting any hits anyway with Search Files on words that are clearly indexed.

Above I am using a test search word that I know works with Apache Solr Attachments ok (but that module does not yet offer the ability to search only within file attachments, hence the interest in Search Files, and also it is simpler not needing a Solr search server running).