looks like you got a memory leak somewhere. i think it's you user controler, which is invoked from loginUser.jsp. Probably you are creating new DataTransactionProxies in an endless loop. just use TransactionAwareProxyFactory() instead, then everything should work fine, the factory will take responsibility of the creation process.
no, seriously - what are you expection people to answer here? your - not so advanced - question is of the type "my car makes strange sounds. how can i fix it?".
try to inspect your code, figure out who is calling whom and debug systematicaly. with eclipse IDE you can set breakpoints on jsps, see what objects are created and where your (most likely) endless loop is...