Upon further research, recent updates to virus definition files cause most virus scanners to now recognise the version of keypress.dll distributed with TeamSpeak as a trojan. Now, the TeamSpeak folks are quite up front about the fact that TeamSpeak does send them some information when you use it, strictly so that they can keep track of how many people are using Teamspeak. The actual trojan being detected is one that sends keypress information to a specific destination, so it is likely that this intentionally trojan-like piece of TeamSpeak is now being recognised as an actual trojan.
In other words, nobody hacked your system, or mine. It is just that a piece of TeamSpeak that has been on your system for however long is now being flagged as a trojan. I don't know if TeamSpeak will function without the keypress.dll file. My guess is that the core functionality will be there, but it won't respond to defined keystrokes, such as key-to-talk, so you will have to stick to voice activation.
