Hi Happy , don't sweat it , the usual reason for this is so many ppl doing updates that the file can become corrupted while in d/l mode off the server.
Make sure you turn off any background applications while trying to update (farm-ville etc
) & temporarily disable any a/v until update has finished installing.
Teamspeak forums can be found here.
http://forum.teamspeak.com/forumdisplay.php/120-Bug-Reports
Have a read through that section , personally I'd try to re d/l the TS update during a quieter period.
As long as you are not using the CELT codec , running an older version is fine , if you are using CELT codec you & all others on the server MUST have release rc1 or greater / or you & everyone you talk to must stay on the old version , these versions of CELT are not compatible with each other.