Char Room Logout Problem

Hi,

I am writing a ASP.NET / Ajax chat room. When users login I add them into a SQL DB Table. When they Logout I delete them from the SQL DB Table. Unfortunately I can't think of a way to execute my logout script if the user leaves their browser inactive longer than the session timeout or if the user closes the browser. If I cant catch these events I could end up with a list of online users which aren't actually online because they didn't logout correctly.

Any help would be greatly appreciated.


 
...