If you add a reference to Microsoft Excel and then try to use it within your ASP.NET application you may receive the following error.
Server Error in '/excel' Application.
Retrieving the COM class factory for component with CLSID {00024500-0000-0000-C000-000000000046} failed due to the following error: 80070005.
The problem is that by default Microsoft Excel as a COM object can only activated by the following accounts:
Administrator
System
Interactive
When you are running your ASP.Net account on Windows XP your web application is running as the ASPNET account.
The way to resolve this issue is to edit the DCOM configuration settings for the Microsoft Excel Application object.
Configure DCOM
Go to the Start-Run menu item.
Type in "DCOMCNFG" and hit enter.
This should load the "Component Services" MMC (you can also load from Administrative Tools - Component Services"
Expand "Component Services"
Expand "Computers"
Expand "My Computer"
Select the "DCOM Config" item
Select the "Microsoft Excel Application" item.
Right click and select Properties
Under "Launch and Activation Permissions" select the "Customize" option.
Click the "Edit" button
Click the "Add" button to add a new account to the list.
On the dialog that is displayed click the Locations button
Click the OK button
On the dialog that is displayed enter "ASPNET" as the account name (make sure location is set to the name of the computer that IIS is on) on Windows XP or
if you are running on Windows 2003 Server you must enter the account that the Application Pool is running as, by default "Network Service"
Now make sure you select the following options for the "ASP.NET Machine Account" or the account that is the application pool identity ( by default Network Service)
Local Launch : Allow
Remote Launch : [blank]
Local Activation : Allow
Remote Activation : [blank]
