What do you need to know?
Wrong question. The right question would be
What should I tell? .
1. You should specify all information about environment you use for Mibew Messenger.
2. You should tell that the issue is browser-independent (or preliminarily check that whether that assumption is correct).
3. You should check for details in the error log of the server (if you have an access to it) and provide them too.
And so on, and so forth.
One should understand that the more details she provides, the higher possibility that anyone would be able to help (and will want to do so).