This is an "experiment" by Google which appears to randomly annoy people who are forced to take part. If you want to take issue with the idiot from Google (Jaime) that thinks it is a good idea you can go to this thread (needs google/gmail login) http://www.google.com/support/forum/p/Web+Search/thread?tid=70ca8ab28e3df1ae&hl=en Hope this helps!
Just came on to say the SAME thing happened to me at work. I also had to enter a code to even get to googles website because our IP was sending them too many requests. Our IP has less then 2K people so thats kind of messed up as well.