It is likely that the problem is somehow related to the way your application is configured (the exception is being thrown when trying to obtain a connection from a pool).
Can you provide a test case (i.e. some code we can deploy which will reproduce the issue)?
Have you tried the latest version, Glassfish 2.1.1?
If you still get the problem with 2.1.1, submit it as a bug to the Glassfish issue tracker (attaching the test case) and we will take a look.
Nigel
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