It was a EJB remote invokation problem.
Retrieving the blob from a local EJB works perfectly.
I have the same issue as you, I'm using Jboss 5.1.2.EAP
1)Could you detailed your changes to resove this exception in jboss 5? someone said
"This is pretty much just a limitation of JDBC blobs. They may not be accessed outside the txn they were retrieved in."
2)For you jboss 7, call from local intercface works, but why remote interface not work?
Sorry for bring this up 2 years later...:D
On JBoss 5 I also get the blob through a local ejb call using the org.hibernate.lob.SerializableBlob class.
I don't know why this not work on JBoss 7 ejb remote calls.