There are 2 reasons this could be happening, you are either not logged into your CMS (this will cause you to d/c everytime you try to connect) and the other is that your securesessions is enabled.
I kept having this problem over and over and I believe I fixed it.
1st. Turn off your emu
2nd. (If your using PhoenixEMU) Open the config.php file where your license info is at and delete your username and password, also do this for the sql settings in the SAME config file then save it.
3rd. (If you use Navicat) Select all the tables and do repair tables (before doing this make sure securesessions is set to 0)
4th. readd all of the correct information back into the config file, mysql name and password and the same for your licesne username and password
5th. Start the emu, load the client and it should allow you to connect.
Hopefully this works for you as it has worked for me.
Honestly if you know how to torrent, just get navicat. It has many more features and makes managing your mysql table 10x easier.How do you fix it using PHPmyAdmin
User DC: System.NullReferenceException: Object reference not set to an instance of an object.
at Phoenix.HabboHotel.Navigators.x1ed94d4060c40d00.xe9f6f6d1c9f8b981(x89adc77c0a5647d3 xd397bb1e465ce45e)
at Phoenix.HabboHotel.Navigators.x04b007c86e91d003.x8f987f90bb700833()
at Phoenix.Communication.Messages.Navigator.x4b1a7075543b5b30.xaeb32f36f12443d3(xca0375af76c32b7d xf16d877ad29a8cf1, x49fa09cbda40e784 x6b03218578435fe3)
at Phoenix.HabboHotel.GameClients.xca0375af76c32b7d.xf896e51a95fce6ae(Byte[]& x4a3f0a05c02f235f)