Hi, I am developing an application in ASP.Net. The problem is my application opens an excel file. It runs fine on my machine (Win Xp) but when I try to run on Windows 2000 , it gives me error <BR><BR>"System.NullReferenceException: Object reference not set to an instance of an object.<BR> at Excel.Workbooks.Open(String Filename, Object UpdateLinks, Object ReadOnly, Object Format, Object Password, Object WriteResPassword, Object IgnoreReadOnlyRecommended, Object Origin, Object Delimiter, Object Editable, Object Notify, Object Converter, Object AddToMru, Object Local, Object CorruptLoad)"<BR><BR>The app is not doing anything fancy..I tested opening a simple file too but it gives me error.<BR><BR>