Welcome aboard. Which Antivirus do you use?
Install Service pack 1. Learn how to install Windows 7 Service Pack 1 (SP1) Service Pack Center - Microsoft Windows
Your crash dumps are not showing any finite probable cause. In such a situation, it is better to enable Driver
Verifier to monitor the drivers
. Driver Verifier - Enable and Disable
Run Driver Verifier for 24 hours or the occurrence of the next crash, whichever is earlier.
Test your RAM modules for possible errors. How to Test and Diagnose RAM Issues with Memtest86+
Run memtest for at least 8 passes, preferably overnight, per RAM module per slot.
Let us know the results, with the subsequent crash dumps, if any.