I had the same problem some days back. I had "NEW TERM" in my aggregate report too. This was when i added a new term mannually through the overture website.
After examining this new term closely, i relaised that it had the same Bid amt, and rank as my new term. i called up overture but did not get a proper expalnation.
If you read the overture statement carefully, u will notice that it say that it takes about 2-3 days for any new word to go online. BUT, mine went online in couple of hours....but this "NEW TERM" started showing up....i even got some converstions on this "NEW TERM". this was really bad for my ROI converstion thingi.
The funny thing is that "NEW TERM" and my new keyword had were given some diffrent immpresions and clicks. and even conversition.
Pesonally, i think it overture error or something...
"NEW TERM" will disapprer in few days.