SQL Server, Password changing and Session timeouts

[asest]

First post on here, hello everyone;
hopefully I am in the right place to find some help.

I have an issue relating somewhat to sessions, password management and SQL Server database using a ASP.NET & VB.NET.

The problem is as follows...

• I want to change my password to my SQL database.
• Everything works with the original password.
• I change the password on the server management and in the connection settings of my respective web page..
• Immediately, everything continues to work.
  
• 15 minutes later... problems.
• I am redirected to my session_timeout page and can not access the database even through SQL Server Management Studio.
  
• I change the password back to its original and everything works fine again, and continues to do so beyond the 15 minute period expressed before.

Note: Sessions are set to timeout after 10 minutes.

My analysis:
Simply, the problem occurs when the session times out.

My solution:
Answer the question as to why the session would timeout and/or why a new session is not generated when re-attempting to login and thereby find a way to fix it.

Any thoughts at all on this would be greatly appeciated,

thank you