Thanks TenPlus1, I really appreciate for your reply :D
Actually before trying your suggestions, I experimented something new and it is looking good till now.
Here is my story:
- After updating my repository I noticed that some new packages were listing in Synaptic Package Manager(might be because of Ubuntu 12.04.3 release).
Then I installed Linux Kernel 3.8.0 by selecting packages:
linux-generic-lts-raring
linux-headers-3.8.0-30
linux-headers-3.8.0-30-generic
linux-headers-generic-lts-raring
linux-image-3.8.0-30-generic
linux-image-generic-lts-raring
and restarted my system. It successfully installed Linux Kernel 3.8
Then I installed all -lts-raring packages for Xserver-Xorg using command prompt:
$ sudo apt-get install libgl1-mesa-dri-lts-raring libxatracker1-lts-raring xserver-xorg-core-lts-raring xserver-xorg-input-all-lts-raring xserver-xorg-input-evdev-lts-raring xserver-xorg-input-mouse-lts-raring xserver-xorg-input-synaptics-lts-raring xserver-xorg-input-vmmouse-lts-raring xserver-xorg-input-wacom-lts-raring xserver-xorg-lts-raring xserver-xorg-video-all-lts-raring xserver-xorg-video-ati-lts-raring xserver-xorg-video-cirrus-lts-raring xserver-xorg-video-fbdev-lts-raring xserver-xorg-video-intel-lts-raring xserver-xorg-video-mach64-lts-raring xserver-xorg-video-mga-lts-raring xserver-xorg-video-modesetting-lts-raring xserver-xorg-video-neomagic-lts-raring xserver-xorg-video-nouveau-lts-raring xserver-xorg-video-openchrome-lts-raring xserver-xorg-video-r128-lts-raring xserver-xorg-video-radeon-lts-raring xserver-xorg-video-s3-lts-raring xserver-xorg-video-savage-lts-raring xserver-xorg-video-siliconmotion-lts-raring xserver-xorg-video-sis-lts-raring xserver-xorg-video-sisusb-lts-raring xserver-xorg-video-tdfx-lts-raring xserver-xorg-video-trident-lts-raring xserver-xorg-video-vesa-lts-raring xserver-xorg-video-vmware-lts-raring libxrandr-ltsq2 x11-xserver-utils-lts-raring xserver-common-lts-raring
it removed already installed Xserver-Xorg packages which was meant for -lts-quantal
Then restarted my system again..
and then.. It works great.. :-)
Till now I have not realized any type of problems, running my system for more than 2 hours.
I think that it was because of Older Linux Kernel and Older Xorg drivers..
I also noticed that it slightly inhanced my system performance. :)
Now I'm able to play games on Wine also(I was not able to play previously), videos are playable as well.
If I will get any type of problem, I will certain use your suggestion.
Thanks again.. :D