Question

I have an Asp.net application which require a third-part .dll from other department(In fact,it is one of the WebSerivce which need the .dll file).

I put the .dll file into the myapp/bin.

Then if I debug this application,it works,there is no error occur.

But once I run the application in normal model( I mean create a virtual dir pointing to my application path in the IIS),I always get the “Service Unavailable” page. And what’s more,the app pool “DefaultAppPool” will be stoped.

I wonder why?

UPDATE:
error id:

Message 1

Source: W3SVC Event ID: 1011 A process serving application pool
‘DefaultAppPool’ suffered a fatal communication error with the World
Wide Web Publishing Service. The process id was ‘5684’. The data field
contains the error number. Error number: 8007006d

Message 2

Source: W3SVC Event ID: 1002 Application pool ‘DefaultAppPool’ is
being automatically disabled due to a series of failures in the
process(es) serving that application pool.

http://support.microsoft.com/kb/885654/en-us

Answer 1

If your dll is unmanaged it needs to be explicitly registered to work within IIS7. Otherwise the appPool will just shut down.

Register and Enable a Native Module on a Web server (IIS 7)

You might have to register a native module if an application on your
Web server requires the behavior supported by the module. After you
register a native module, that module will be loaded and available in
every application pool on the server, but you must also enable it by
adding it to the list on the Modules feature page. For example, you
might have a custom authentication module that an application
requires. You must register the .dll file, and then enable the native
module to run. You can then enable the module at any level at which
the module is needed, such as at a site or an application level.