Try to run A.V.A. through NWZLauncher located here: C:\AeriaGames\AVA
If that doesn't work try to Reinstall;
If Reinstall don't work do the following:
1. Go here: http://www.aeriagames.com/contact/support
A.V.A. in English
The server you play on
5. Character Name:
Your In-Game name
6. Date and Time
*Date and Time the issue occurred*
In this part, make sure you give all the detail and necessary information you think Aeria should know, like the link of the image you have on this post showing the error, when did the error actually happened (On entering A.V.A., On leaving A.V.A., on joining a channel, on joining a room...), etc...
9. "Send Email."
10. Wait some hours until Aeria answer you.
Hope you get your error fixed.