hi ramkumar,
make sure all your drivers are up to date by checking device manager. You can get to device manager by right clicking in the bottom right or by pressing Windows + X and choosing device manager. You'll see drivers that need installed as their catergories will be explanded and they'll have a yellow warning next them. You can right click them to have windows automatically find updates for them.
Windows update doesn't always pull down the latest updates for Radeon Graphics so visit Link Removed fill out the form and install the latest driver.
Do you still have your recovery discs that came with your laptop?? HP doesn't support Windows 8 on computers manufactured before Oct. 2011. If its not a drivers issue, it could be...