I got this exception last week when I was writing a task service to perform a task that involves retrieving data from a database. I found the SQL statements that it try to run from the The log files. They worked fine and gave correct results when I run it from SQL Server Management Studio.Then I googled the exception and found following details are helpful.
Most of the time this exception occur because of a timeout.
You can fix it by increasing the value of transactiontimeout property in conf/jboss-server.xml.
more info: http://ttlnews.blogspot.com/2012/04/jboss-exception-transaction-is-not.html
Another possible scenario is that there is a Null Pointer Exception in the flaw of your application. This caused the transaction to end and re-enter a loop when the transaction was not active.
more info: http://thejavablog.wordpress.com/2010/04/05/transaction-is-not-active-txtransactionimple-ac-basicaction
