For the project i am working on we created an Authorization component which loads as Http Module and works on the user credentials.
The module was defined in web.config for the web application and was working fine. Until one day i tried to play with App pool settings of IIS and then the module just stopped loading.
After doing some searches on web i finally figured out the problem. While playing with the App pool settings i had changed it to run in Integrated mode from the Classic mode.
When i run my application pool in the Integrated mode the module has to be specified in web.config as an entry under system.webserver tag while if i am using the classic mode the http module has to be specified under system.web tag of web.config.
How this matters and what these 2 modes mean is something i still have to figure out but for now i am happy that my module is up and running for me to go ahead and work on my tasks :)