Hi,
Try running this SQL Script against your ReportServer Database, it should show you the required details.
SELECT a.UserName, a.Format, a.TimeStart, b.Name, b.Description, a.[Parameters], a.TimeStart
FROM ExecutionLog a INNER JOIN Catalog b ON a.ReportID = b.ItemID
ORDER BY a.TimeStart DESC
Eric UNG [Senior Analyst Programmer :: Sydney, Australia]