I am having this issue of lag in Windows 7 Professional, the CPU usage is 100%, even if I am only watching video on GOM player, nothing else is open, but the usage is 100%, or if I open Firefox/Chrome the usage becomes 100%, I need to restart the system to get rid of this. It occurs many times a day.I thought that windows might have the issues, I installed it twice but the same issue occurs. My friend told me that it might be low voltage issue, but even on battery power, I am having the 100% usage issue.
(System Specs : core i5, 4GB ram, 500GB HDD, intel HD card)
I am uploading image of my task manager: