More info would be usefull.
- Wich Core version are you using?
- Did you grab it from the official repo?
- Wich DB Version are you using?
- Is it the official one?
- Did you applyed all updates to the world db, characters db and auth db?
- Wich system have you?
Note: Before you post, read the sticky's. It is said to give the maximum info you can (OS, MySQL version, etc...)