Firebird hangs

I've developed a application using delphi and firebird 2.5.
While coding in delphi i had followed a practice of closing the adoconnection and adoquery after each operation. For example if add a record, i would open connection add the record and close the connection.The reason being if the connection is lost i wont get a connection time out error. i'm also using ado commit to process my request.

I have observed that on added a record whan i go for the second both the node and the server program hangs. On closing the node the situation returns to normal. I'm wondering if my code of opening and closing connection is causing the problem.
please advise