Correlate the error in FileReader log with the ScanDetail log, and check to see if the file was actually scanned:
ScanDetail log
"Apr 21, 2009 11:17:53 PM","INFO","scan name 04/21/09 - 8:00 PM","COMPLETED_ITEM","//somecomputer\someshare\somefile' ","268800","","","",""
The reason for this error is that the target share is not allowing SID lookup. A way to correct this problem is to do the lookup from the discover server itself. Modify the crawler.properties in \vontu\protect\config directory as follows:
filesystemcrawler.localusernamelookup = true
Restart the Vontu Monitor service after making this change.