you can set photo shop to use less ram when in use , open ps ,go to edit/preferences /memory and image cache,in the amount of ram ps uses [default 50%],click and drag it to about 25%, might help a bit when multi tasking

also i use staup lite to end program not need to be running all the time .might help
http://malwarebytes.org/startuplite.php

Hi thank you very much for your valuable help .Yes I do agree with you but every time installs OS newly my PC works good but after some time lets say after two weeks it starts giving problem it means either it is getting affected by the virus or the Current OS which i am installing is not good .For the virus i got Escan Antivirus software i am confident that it is good enough. So now come to the conclusion that either OS is not good or mine motherboard or Processor has some problem .
Thanks guys I am marking this thread as Solved but pls do reply me if you think any else
thanks again