Yeah. Mavericks. I upgraded yesterday to Mavericks from ML and experienced countless bugs and problems. Felt like i was running a Developer Preview. It became so bad that I had to do a clean install to see if that did the trick. And it did, Mavericks is running somewhat faster...yes it still has bugs though but not as much as I previously had. I think Apple should hurry up with 10.9.1 update with bug fixes.