Mods are unrelated in causing that issue. It'll happen without mods too.
It's WG's issue and has been ongoing for a loooooooooooooooong time. And they simply don't seem to care at all. (Sure, they've posted in a thread about it.. but nothing is being done.)
This post is 4 months old, for example; http://forum.worldoftanks.eu/index.php?/topic/659819-chat-issues-2401/
And there was threads before that too.