display problem after installaling updates in ubuntu 12.04

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http://askubuntu.com – i had installed ubuntu 12.10 yesterday but it was not working properly, so installed ubuntu 12.04 from Live USB and after installation, it was working without harm, but problem arose whene i installed updates, the screen is going weird if i lounch dash home. i've posted link of screen shot of my screen (because i am not allowed to attach here), hoping that this problem can be solved. http://samsher.xtgem.com/pics/problem.png take a look at top of the screen, there you can see the problem. lspci -nn | grep VGA output 00:0d.0 VGA compatible controller [0300]: NVIDIA Corporation C61 [GeForce (HowTos)