I'm missing System spec's but if you can and feel comfortable doing it... how about checking your system for dust/dirt and making sure the Graphical card/GPU is running with ok temps?
I've seen systems completely clogged up within a year, depending on their environment... and as the problems do seem to arise when you are stressing it...
Maybe keep track of temps with something like HWMonitor?
+... looking at last dump.. I don't think your drivers were updated correctly:
Unable to load image \SystemRoot\system32\DRIVERS\atikmdag.sys, Win32 error 0n2
*** WARNING: Unable to verify timestamp for atikmdag.sys
*** ERROR: Module load completed but symbols could not be loaded for atikmdag.sys
Probably caused by : dxgmms1.sys ( dxgmms1!VIDMM_GLOBAL::UnreferenceDmaBuffer+7d )
When upgrading your graphic driver you MUST remove all traces of the current driver. In order to do that we recommend using Driver Sweeper
Driver Sweeper is a fast tool to remove driver leftovers from your system. It's very important to remove your drivers on a proper way, because driver leftovers can cause problems like stability and startup problems. You can use it if you want to update/remove drivers from your system.
How to use ?
There are two methods to use Driver Sweeper.
Both methods achieve the same results. This method is always able to clean all files.
This method will delete remaining files upon reboot (if deleting failed). You can clean your drivers this way:
- Use the official uninstaller(s) of the driver(s) you want to uninstall.
- Reboot your PC in Safe Mode.
- Run Driver Sweeper and select what to clean.
- Analyse lists all the entries possible to remove, cleaning removes the entries selected.
- More drivers can be selected for the same cleaning process.
What can it be used for ?
The current supported drivers are NVIDIA (Display and Chipset), ATI (Display), Creative (Sound) Realtek (Sound), Ageia (PhysX) and Microsoft (Mouse).
http://phyxion.net/Driver-Sweeper/Driver-Sweeper/Version-3-1-0/
When it is removed then download and install the fresh copy
ati driver