SEVERE: Can't lookup new HighLowSequence for field id using sequence name SEQ_t_xx_xxx

Hi,

we have a Problem with Tomcat/MySQL which causes our webapplication to stop working.
After a restart of Tomcat and MySQL it works again. But we have to do this a few times a day.

First some Info about the Server and versions:
- SUSE LINUX Enterprise Server 9 (i586) Patchlevel 4
- jakarta-tomcat-5.0.19-29.18
- mysql-shared-4.0.18-32.37
- java2-jre-1.4.2-129.48
- java2-1.4.2-129.48


Often the follow error occurs the application is blocked:

Mar 12, 2009 9:25:19 AM org.apache.ojb.broker.util.logging.CommonsLoggerImpl error
SEVERE: Can't lookup new HighLowSequence for field id using sequence name SEQ_t_xx_xxx
org.apache.ojb.broker.TransactionInProgressException: Connection is already in transaction
        at org.apache.ojb.broker.accesslayer.ConnectionManagerImpl.localBegin(Unknown Source)
        at org.apache.ojb.broker.core.PersistenceBrokerImpl.beginTransaction(Unknown Source)
        …

This error is always in relation with the following warnings:

12 Mar 09:20:31  22794068 [http8080-Processor16] WARN  ch.XXX.XXX.dh.PersistenceSession  - org.apache.ojb.broker.PersistenceBrokerException: org.apache.ojb.broker.accesslayer.RsIterator$ResourceClosedException: Resources no longer reachable, RsIterator will be automatic cleaned up on PB.close/.commitTransaction/.abortTransaction
12 Mar 09:25:19  23081606 [http8080-Processor16] INFO  ch.XXX.XXX.dh.PersistenceSession  - Transaktion abgebrochen
12 Mar 09:25:19  23081606 [http8080-Processor16] WARN  ch.XXX.XXX.dh.PersistenceSession  - org.apache.ojb.broker.PersistenceBrokerException: Error while try to assign identity value
12 Mar 09:25:19  23081606 [http8080-Processor16] WARN  ch.XXX.XXX.servlets.BestellungSaveServlet  - Error while try to assign identity value

Does anybody have a hint?

Thank you