Deleting files when user leaves site.

This is all being done for a private network, but here is the scenerio:

Users use the site to request access to different things.

Depending on what they select, different forms need to be filled out.

The forms are then sent as attachments in email to the appropriate people.

Everything works fine.......

Except....

I use ASP sessions to keep track of the different forms. Upon creation of the first form, a directory is created with the session number. All other forms are stored in this directory.

Once the final SUBMIT button is pressed, and the forms emailed, the directory is deleted.

My issue is, if someone fills out one form (therby creating the directory, and 1 file) then decides they will do it later, and either (A) close the browser, or (B) navigate to a different site and later close the browser, the directory and file will be sitting out there forever, until I manually delete them.

Is there a way to end the session and delete the folder whenever someone closes their browser, or navigates away from the site?

Thanks!

CJ