Web applications are not good for this sort of task. Web application
response to client requests and doing something with them outside of client
requests is not what they are for.

Typically, you would either use Windows scheduler or make your own Windows
service.

What you describe should not be part of the webserver process because it
would be a bad design. You want to trigger a Process X that does something.
So use database triggers, task planer or create an own processes or windows
service that implements the Process X. Encapsulate your logic you wanted to
do in your web application into a assembly and reference it to your process.

As with the others, I have to agree that creating your own services would
probably be a good idea for this. You could have the web app start the
service using the system.serviceprocess.servicecontroller class and then
have that service take over from there with its own timer and, after the
elapsed time, shut itself down. I've created similar services like this
before and its fairly easy (in most cases I'm sure).

If you need further assistance, reply back.

HTH,
Jim