Without knowing the exact issue you're talking about, it's difficult to say more, but at the very least you should
definitely upgrade your installation. It is always best to stay with the most recent GA release--that way you'll have all of the latest fixes, including the latest security fixes.
The current releases are MySQL 5.1.73, MySQL 5.5.36, and MySQL 5.6.16. I'd recommend you consider upgrading to 5.6.16, since this is the latest GA, unless there is some great need for you to remain with 5.1, since this series has just been EOL'ed (5.1.73 is supposed to be the final 5.1 release).
In any case, 5.1.47 was released in May 2010. That's quite old. You REALLY should upgrade. :)
cheers
jon.
Jon Stephens
MySQL Documentation Team @ Oracle
MySQL Dev Zone
MySQL Server Documentation
Oracle