Hi,
Our users get random error pages from vibe/tomcat (Error 500).
If the user tries it again, it works without an error.

here are some errors from catalina.out:

Code:
.....
2013-07-31 06:23:12,225 WARN  [http-8080-8] [org.hibernate.util.JDBCExceptionReporter] - SQL Error: 1206, SQLState: HY000
2013-07-31 06:23:12,225 ERROR [http-8080-8] [org.hibernate.util.JDBCExceptionReporter] - The total number of locks exceeds the lock table size
2013-07-31 06:23:12,242 WARN  [http-8080-8] [org.kablink.teaming.web.portlet.handler.LogContextInfoInterceptor] - Action request URL [http://vibe.*******.ch/ssf/a/do?p_name=ss_forum&p_action=1&entryType=4028828f3f0ed66d013f0f3ff208013d&binderId=2333&action=add_folder_entry&vibeonprem_url=1] for user [kablink,ro]
2013-07-31 06:23:12,245 WARN  [http-8080-8] [org.kablink.teaming.spring.web.portlet.DispatcherPortlet] - Handler execution resulted in exception - forwarding to resolved error view
org.springframework.dao.InvalidDataAccessApiUsageException: object references an unsaved transient instance - save the transient instance before flushing: org.kablink.teaming.domain.FolderEntry; nested exception is org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: org.kablink.teaming.domain.FolderEntry
	at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:654)
	at org.springframework.orm.hibernate3.HibernateAccessor.convertHibernateAccessException(HibernateAccessor.java:412)
	at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:411)
........
2013-07-31 06:23:36,474 ERROR [Sitescape_QuartzSchedulerThread] [org.quartz.core.ErrorLogger] - An error occured while scanning for the next trigger to fire.
org.quartz.JobPersistenceException: Couldn't acquire next trigger: The total number of locks exceeds the lock table size [See nested exception: java.sql.SQLException: The total number of locks exceeds the lock table size]
	at org.quartz.impl.jdbcjobstore.JobStoreSupport.acquireNextTrigger(JobStoreSupport.java:2794)
	at org.quartz.impl.jdbcjobstore.JobStoreSupport$36.execute(JobStoreSupport.java:2737)
	at org.quartz.impl.jdbcjobstore.JobStoreSupport.executeInNonManagedTXLock(JobStoreSupport.java:3768)
	at org.quartz.impl.jdbcjobstore.JobStoreSupport.acquireNextTrigger(JobStoreSupport.java:2733)
	at org.quartz.core.QuartzSchedulerThread.run(QuartzSchedulerThread.java:264)
Caused by: java.sql.SQLException: The total number of locks exceeds the lock table size
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:946)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2870)
	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1573)
	at com.mysql.jdbc.ServerPreparedStatement.serverExecute(ServerPreparedStatement.java:1169)
........
2013-07-31 06:27:12,463 WARN  [Sitescape_Worker-8] [org.hibernate.util.JDBCExceptionReporter] - SQL Error: 1206, SQLState: HY000
2013-07-31 06:27:12,463 ERROR [Sitescape_Worker-8] [org.hibernate.util.JDBCExceptionReporter] - The total number of locks exceeds the lock table size
2013-07-31 06:27:12,463 ERROR [Sitescape_Worker-8] [org.jbpm.graph.def.GraphElement] - action threw exception: Hibernate operation: could not execute update query; uncategorized SQLException for SQL [update SS_ChangeLogs set owningBinderKey=?, owningBinderId=? where (entityId in (? , ?)) and entityType=?]; SQL state [HY000]; error code [1206]; The total number of locks exceeds the lock table size; nested exception is java.sql.SQLException: The total number of locks exceeds the lock table size
org.springframework.jdbc.UncategorizedSQLException: Hibernate operation: could not execute update query; uncategorized SQLException for SQL [update SS_ChangeLogs set owningBinderKey=?, owningBinderId=? where (entityId in (? , ?)) and entityType=?]; SQL state [HY000]; error code [1206]; The total number of locks exceeds the lock table size; nested exception is java.sql.SQLException: The total number of locks exceeds the lock table size
	at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:83)
	at org.springframework.orm.hibernate3.HibernateAccessor.convertJdbcAccessException(HibernateAccessor.java:424)
.......
2013-07-31 06:27:22,393 INFO  [CT-kablink] [org.kablink.teaming.lucene.LuceneProvider] - (kablink) Committed, firstOpTimeSinceLastCommit=1375251142310, numberOfOpsSinceLastCommit=12. It took 82.62174 milliseconds
2013-07-31 06:28:22,686 INFO  [Sitescape_Worker-9] [org.kablink.teaming.jobs.CleanupJobListener] - Removing job send-email.sendMail-1375252102500
2013-07-31 06:29:51,309 INFO  [Sitescape_Worker-10] [org.kablink.teaming.jobs.CleanupJobListener] - Removing job send-email.sendMail-1375252191099
2013-07-31 06:32:08,820 WARN  [http-8080-2] [org.hibernate.util.JDBCExceptionReporter] - SQL Error: 1206, SQLState: HY000
2013-07-31 06:32:08,820 ERROR [http-8080-2] [org.hibernate.util.JDBCExceptionReporter] - The total number of locks exceeds the lock table size
2013-07-31 06:32:10,775 WARN  [http-8080-1] [org.hibernate.util.JDBCExceptionReporter] - SQL Error: 1206, SQLState: HY000
2013-07-31 06:32:10,775 ERROR [http-8080-1] [org.hibernate.util.JDBCExceptionReporter] - The total number of locks exceeds the lock table size
2013-07-31 06:32:12,305 WARN  [http-8080-1] [org.hibernate.util.JDBCExceptionReporter] - SQL Error: 1206, SQLState: HY000
2013-07-31 06:32:12,305 ERROR [http-8080-1] [org.hibernate.util.JDBCExceptionReporter] - The total number of locks exceeds the lock table size
2013-07-31 06:32:14,605 WARN  [http-8080-3] [org.hibernate.util.JDBCExceptionReporter] - SQL Error: 1206, SQLState: HY000
2013-07-31 06:32:14,606 ERROR [http-8080-3] [org.hibernate.util.JDBCExceptionReporter] - The total number of locks exceeds the lock table size
2013-07-31 06:32:16,056 WARN  [http-8080-3] [org.hibernate.util.JDBCExceptionReporter] - SQL Error: 1206, SQLState: HY000
2013-07-31 06:32:16,056 ERROR [http-8080-3] [org.hibernate.util.JDBCExceptionReporter] - The total number of locks exceeds the lock table size
2013-07-31 06:32:24,166 WARN  [http-8080-1] [org.hibernate.util.JDBCExceptionReporter] - SQL Error: 1206, SQLState: HY000
2013-07-31 06:32:24,166 ERROR [http-8080-1] [org.hibernate.util.JDBCExceptionReporter] - The total number of locks exceeds the lock table size
2013-07-31 06:32:24,167 WARN  [http-8080-1] [org.kablink.teaming.spring.web.portlet.DispatcherPortlet] - Handler execution resulted in exception - forwarding to resolved error view
org.springframework.jdbc.UncategorizedSQLException: Hibernate flushing: could not insert: [org.kablink.teaming.domain.AuditTrail]; uncategorized SQLException for SQL [insert into SS_AuditTrail (zoneId, startDate, startBy, endBy, endDate, entityType, entityId, owningBinderId, owningBinderKey, description, transactionType, fileId, applicationId, deletedFolderEntryFamily, type, id) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 'A', ?)]; SQL state [HY000]; error code [1206]; The total number of locks exceeds the lock table size; nested exception is java.sql.SQLException: The total number of locks exceeds the lock table size
	at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:83)
	at org.springframework.orm.hibernate3.HibernateTransactionManager.convertJdbcAccessException(HibernateTransactionManager.java:805)
	at org.springframework.orm.hibernate3.HibernateTransactionManager.convertHibernateAccessException(HibernateTransactionManager.java:791)
	at org.springframework.orm.hibernate3.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:664)
....

It always logs the Mysql error code 1206:
MySQL :: MySQL 5.4 Reference Manual :: 13.6.12.1 InnoDB Error Codes

1206 (ER_LOCK_TABLE_FULL)
The total number of locks exceeds the lock table size. To avoid this error, increase the value of innodb_buffer_pool_size.
The value of innodb_buffer_pool_size is set to 8388608 (8MB) on my server.
In the documentation (MySQL :: MySQL 5.4 Reference Manual :: 13.6.3 InnoDB Startup Options and System Variables) it says that the default is 128MB.

Can i set the value to 134217728 (128MB) or will this cause other problems? Will this setting solve my problem?

Thanks for your help.