BSOD Playing Hearthstone and watching twitch.tv

Hi, well its not realy a BSOD, BUT A FREEZE

Hellow there, after a long time of ignoring this problem, i'm so done with it and tired of it, so here we go, ill try to explane it.

My Problem:
When i am playing a game like Hearthstone or World of warcraft on my Right monitor, and watching a stream/youtube vid on my left screen, suddenly my computer freezes. Afther that i need to manualy shut down my computer (pushing the off button) and reboot it.

The last 3 times it happened i was Playing Hearthstone and World of Warcraft.
Just a few moments ago it also happens when i was watching a youtube vid on my left screen (21inch) and watching my facebook on my right screen (24inch)

So.

The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.

Details:

HTML Code:

- <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
- <System>
  <Provider Name="Microsoft-Windows-Kernel-Power" Guid="{331C3B3A-2005-44C2-AC5E-77220C37D6B4}" /> 
  <EventID>41</EventID> 
  <Version>2</Version> 
  <Level>1</Level> 
  <Task>63</Task> 
  <Opcode>0</Opcode> 
  <Keywords>0x8000000000000002</Keywords> 
  <TimeCreated SystemTime="2014-03-04T14:33:41.356403300Z" /> 
  <EventRecordID>63014</EventRecordID> 
  <Correlation /> 
  <Execution ProcessID="4" ThreadID="8" /> 
  <Channel>System</Channel> 
  <Computer>baas-PC</Computer> 
  <Security UserID="S-1-5-18" /> 
  </System>
- <EventData>
  <Data Name="BugcheckCode">0</Data> 
  <Data Name="BugcheckParameter1">0x0</Data> 
  <Data Name="BugcheckParameter2">0x0</Data> 
  <Data Name="BugcheckParameter3">0x0</Data> 
  <Data Name="BugcheckParameter4">0x0</Data> 
  <Data Name="SleepInProgress">false</Data> 
  <Data Name="PowerButtonTimestamp">0</Data> 
  </EventData>
  </Event>

PC specs:

OPERATING SYSTEM:
Windows 2.6.1.7601 (Service Pack 1)
CPU TYPE:
Intel® Core™ i5-3570K CPU @ 3.40GHz
CPU SPEED:
3.42 GHz
SYSTEM MEMORY:
8.54 GB
VIDEO CARD MODEL:
NVIDIA GeForce GTX 660 Ti
VIDEO CARD MEMORY:
4.24 GB
VIDEO CARD DRIVER:
nvd3dum.dll
PRIMARY DISPLAY RESOLUTION:
1920x1080
SECONDARY DISPLAY RESOLUTION:
1680x1050

I hope someone can help me with that.

And sorry for my bad english.
Kinda regards.
Sven.