It looks like you may have a damaged Outlook file.
A quick Google search (You DID do that for yourself, didn't you) gives these results.
http://www.google.co.uk/search?hl=en&safe=off&q=use+scan.pst.exe&btnG=Search&meta=&aq=f&aqi=&aql=&oq=&gs_rfai=
http://office.microsoft.com/en-us/outlook/HA100758311033.aspx
http://office.microsoft.com/en-us/outlook/HA100758311033.aspx
JOhn, April 2010