My Dell Vostro laptop keeps on restarting when I'm busy using it without commanding it to do so. I'm using windows 7 for O.S.
What might be the problem? How can I solve it?
This sort of question is very hard to diagnose with this amount of information. You would be best served taking it to a computer shop to get it examined.
Normally when I faced such issue it what Heating Up soon.
Just check if Fan at base(or wherever) are rotating fine... try installing some CPU Heat Diagnostic tools like: http://core-temp.uptodown.com/en
would advice to get it repaired if its Heating issue... delay could cost you a lot