This has to be strangest issue I have had in Linux, a fight that took a long time to win, and one which I almost lost. Apparently, it is the developers of the fgrlx driver, the proprietary graphics driver are at fault. A bug in Intel chipsets incorporated a change in the driver, which wreaked havoc with users of ATI chipsets. The minimise, maximise, and alt+tab were ridiculously slow. There was seemingly no way to correct this problem. On googling, I found that it was a very irritating problem. There was a correction in the driver, which could correct this problem. I had a tardy time, trying to understand the instructions, and executing them. At one point of time, I actually felt like giving it up. All the Keyservers, which were essential in the solution were not working. At the point of maximum frustration, it seemingly worked, and now, the problem has been corrected.
Add These Lines in the sources.list file
deb http://ppa.launchpad.net/launchpad-weyland/xserver-nobackfill/ubuntu karmic main
deb-src http://ppa.launchpad.net/launchpad-weyland/xserver-nobackfill/ubuntu karmic main
Then, sudo apt-get update
Then, sudo apt-get install xserver-xorg-core
Then restart, enable desktop effects and the u have linux working like a charm…