When I try to insert a record, I get this error : The underlying provider failed on Open. This error occurs only with IIS and not with VWD 2008\'s webserver. In the EventViewer
Using new instance of DB Entity on every action should not physically create connection to your SQL server. Entity Framework will use connection pool created for your (process, app domain, connection string) as configured in your connection string to avoid creating new connections.
This issue is very environmental and tweaking parameters (in your conn string) like below should resolve the problem-
Min Pool Size=1;
Max Pool Size=100; // default
Connect Timeout=15; // in seconds
Pooling=true;