ASP.net proper login - logout classes - control login status
In addition to losing the hungarian notation there are a few things worth mentioning:


Don't use try-catch construction with empty 'catch' clause. It is almost always a bad idea to hide an exception if it was thrown. 
It would be better to check explicitly if the key is in the collection using appropriate methods. BTW exception handling is quite expensive speedwise and explicit checking will work faster.
Try to refactor your controlOfLoginStatus() method into several distinct functions with more meaningful purpose.
Refactor your database code into separate class.
Use parameterized queries while working with database. It will save you from sql injections and it will make your queries run faster.