Ruleaza sp_spaceused cu parametrul "updateusage" = "true" - http://msdn.microsoft.com/en-us/library/ms188776.aspx
Vezi daca te ajuta
http://stackoverflow.com/questions/1368354/excessive-reserved-space-on-sql-server
http://www.sqlservercentral.com/Forums/Topic600468-5-2.aspx