I've had the same problem.
I have found that the cause appears to be related to hitting mouse button 4(i.e. back button) while on the secondary machine. This is also the key I have for Push to talk on Teamspeak.
It only seems to occur If I hit push to talk while on the other machine. When I return to the primary, I see that teamspeak is locked up and I have to restart it.
Hopefully this info helps people, as I still use both programs together, I just try not to use push to talk on secondary machines.