mysql deadlocks started after upgrade from 5.0 to 5.1

Old server: We w开发者_JAVA百科ere using mysql 5.0.77 for more than a year - centos New server: We have upgraded our server and came with mysql 5.1.49 - ubuntu recently.

Both mysql server configs are defaulted except active query cache and general log. All our tables are innodb. We use Zend framework and php calls from apache2 prefork.

After upgrade suddenly we are started getting deadlocks and loosing critical database records. Can't derive on what exactly has caused so many deadlocks every few hours when our old server had no such problems.

Please suggest what could have caused this behaviour and/or how to resolve this.