Version: (using KDE 4.1.3) OS: Linux Installed from: Ubuntu Packages I'm using an Nvidia GeForce 6600 FX, so I'm not sure if this is related to the Nvidia proprietary driver or not. To reproduce, you need Kwin desktop effects on. Also, enable the "show paint" effect. Next, start kmail and enable the system tray option. Click the close button on kmail to minimize it to the system tray, and the entire screen will start flickering, repainting continuously, causing the CPU usage of kwin and X to climb. Stopping desktop effects and restarting it makes it go away, but anytime kmail is minimized to the tray, it returns.
*** This bug has been marked as a duplicate of bug 177985 ***