Adobe Photoshop CS4. It's annoying as shit. If you have CS3, keep it. I downgraded PS on my Mac and I'm about to reinstall it on my PC as well. The CS4 suite itself is nice, but they made the interface really regular, removed the extract tool by default (though you can install it as a plugin from a previous CS3 install), and they moved some things where they didn't really need to. It starts raping your system processes on idle every once in a while, too.