Windows reinstall kar lavo. clean install karyo. Format kar ke. Antivirus windows defender rehen deyo windows 7 wala. ik USB security wala install kar leyo.
One of your ram is faulty....nothing else remove that one all will be fine....as per you 3 gb hai to pehle 1 gb hata nd try agar na solve hove then swap....if they are 3 thn sabko try kar agar 2 or 3 ram hongi do with all..... baki win ki koi prob nahi hai ye nor software so try this your problem will be solved.