About a week ago I installed Lion Developer Preview 4. Since then, whenever I am just browsing the web, checking my email via Postbox or talking to someone on MSN, the fans will roar up for seemingly no reason. When I open Activity Monitor, CPU idle is at about 80% with the kernel using about 16%, and after two refreshes idle goes up to ~98% and then the fans go down. When I close activity monitor, the fans start roaring back up in 20 minutes or so. If I leave activity monitor open, the fans do not roar back up. What the heck is going on?