Scan to PDF showing wrong scan data

Hi All,  

We are having an issue with a Wrokcentre 3325.  We are scanning about 12,000 pages per month,  At least once a week our user will scan a set of documents (usually in the 30-50 pages in size).  And the resulting PDF is the data from an earlier  scan (sometimes even from a few days earlier).  I have checks the file creation dates and they are current, showing that the scan was just created but I am at a loss as to where it is finding this old data from (we have the users physicaly turn off the machine daily).  

Any thoughts ?