It's been months since I've been RECEIVING "A disk read error occurred. Press Ctrl+Alt+Del to restart" error and I don't know exactly why. This error OCCURS MINIMUM 2-3 times a week and the only solution I find to remove is to wait for sometime and restart my computer again and again for at least 5-6 times. Now I'm a bit confused that whether this problem is associated with my HDD only or some other hardware too.

Also, even if my computer starts and works in its normal phase it lags a LOT! even with programs like Chrome.

PC Specs:
Operating System: Windows 8.1 64-bit
Motherboard: Gigabyte B85M-DS3H
Memory: 8192MB RAM
Card name: Intel(R) HD GRAPHICS 4600
HardDisk: 500 GB

I basically use my computer for video editing with softwares like AfterEffects, Premiere pro etc.Hi
You could check the hard drive with  HDtune pro trial from here  http://www.hdtune.com/
First check the hard drive health anything highlighted in red is of concern .
If everything in the health list is ok. Run the bench MARK that will show how fast the hard drive is reading over the whole surface of the disks.
If you are going to need to replace the hard drive  consider downloading a copy of EaseUS Todo Backup Free 9.1 from here

http://www.todo-backup.com/products/home/free-backup-software.htm

This will help you backup or copy the hard drive