With Macromedia ColdFusion MX 6.1, if a data source is configured to maintain connections and the number of connections are limited (under Advanced Settings in the data source), it may cause the server to hang when trying to get a new connection, particularly if the server is under load. The TechNote below will explain why the problem occurs and what to do about it.
ColdFusion MX 6.1: Hot Fix for Data Source Connection Pooling