Excel Interop Dll problem 2003

[smtwtfs007]

Guys,

I am having problems with Excel 2000 to Excel 2003 dll in production.

I am having version 2003 in my PC and I used the below code change to
open password protected excel files in my application. My application
is in ASP.NET

From:
objExcel = New Excel.Application
objExcel.Workbooks.Open(strFileName, , False)
To:
objExcel = New Excel.Application
objExcel.Workbooks.Open(strFileName, , False, ,
file_pwd.Trim)

The above change is working fine in my local PC.

I moved the code change into production where I had Excel 2000
version.

It did not work. I got an error:

Object reference not set to an instance of an object. 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) at
SentryDotNet.FileParsing_FTP.FTPLoadFile(String strFileName, Int32
intClientID)
So I requested for Excel 2003 version in production and Server team
has installed Version 2003 in production server

Now I am getting different error as below

Server execution failed at
SentryDotNet.FileParsing_FTP.FTPLoadFile(String strFileName, Int32
intClientID)

I am really worried. I called server team and found out that they did
not restart the server after they installed 2003 version the reason
being it had not asked for restart.

Do we have to restart the server after installing 2003?

How to resolve the above issue?

Please help.. Do we have to register the Excel dll into production?
How to do this?

Please help.

Thanks.