Can you tell us how to setup the user in the 5.5 box, I have some application running without problem, and I guess it may be cause by some wrong setting when you setup the use in MySQL...... I have the same problem when I first play with some applications.
Try to set up a new use and change the application setting like :
mysql> GRANT ALL PRIVILEGES On DB-name.* to DB-user@192.168.1.123 IDENTIFIED BY "password";
mysql> CREATE DATABASE DB-name;
??
See if this help ?
Best Regards,
Paul T.C.Fung