Windows 7: Windows 7 x64 freezes from time to time

I have a problem with Win 7 freezing when I run multiple programs. (eg. media player and windows explorer) It was working fine until a few days ago so I did a system restore to the last known date that it was working and it still freezes from time to time.ANNOYING!!!!
My setup:
AMD Phenom ii x6 1090t
Biostar TA880GB+ MOBO
16gb Gskill Ripjaws 1333Mhz
2- 500gb WD 7200rpm
Evga Nvidia GTX 550 ti

Help please

Hello kade616,

*Have you checked in Event Viewer?
Type eventvwr in search.
Go to the Windows Logs > application > in the left hand column note anything that relates to the problem.
Please note the event ID, and the source codes and tell us what they are.

*List all the Security software you have ever had installed & currently have now on your computer please.

* Browser addons can create problems.
Check how many you have on your various browsers.
Is each & every one really needed?

* Go to search, type device manager and look for any yellow warning markers.

* Run a system file check to verify and repair your system files.
To do this type cmd in search, then right click to run as administrator, then
SFC /SCANNOW

SFC /SCANNOW Command - System File Checker

* Check Disk.

Disk Check