Right click on your speaker icon (lower right corner of your screen next to your clock), left click on "playback devices", open TS3 and verify that you have a playback device selected for "Default", and "Communication", you should see the bar graph to the right of a device move when you have TS3 open and someone is speaking. Make sure that device is your communication device.
On a side note you can click on recordings and see the recording graph move...make sure it is also your communication device.
The last thing to check is click on the tab labeled Communication and make sure "Do Nothing" is selected.
Let me know how you make out,
jn