Macbook pro 13" late 2011 freezes

Hi folks

MacBook Pro (13-inch, Late 2011)

2.4 GHz Intel Core i5

GB 1333 MHz DDR3

Intel HD Graphics 3000 512 MB

My Macbook was all working fine being my primary workhorse, off lately the system freezes, varies from a few secs to a few mins, becomes totally unresponsive, neither the keyboard nor the mouse cursor function, and then later comes back to normalcy only freeze sooner or later.

didnt find any solution on the internet, only last resort is am shutting down the system everynight after work, which i normally never used to do it ealier.

and now even before i could finish this, the system froze 6 times.

any help is much appreciated.

thank you