Got the same problem here.
Totally random but most of the time it happens when I want to switch between chat channels (so when i typ /map or /party).
My screen freezes but the sound keeps on playing. I’ve to CTRL + ALT + DEL to stop GW2. After that I can restart GW2 and start playing again.
Please help with this issue, The most annoying thing about it is that you get kicked out of WvWvW and have to start over in the queue!
If it can’t be fixed in a short time, My suggestion is a “saved slot” for WvWvW when you aren’t logged off correctly, that would be great :P.