Hi okrgr & Welcome to the forums ^_^,
I have analysed your dump files and below has been provided an analysis of the same for informative purposes :-
SYSTEM_THREAD_EXCEPTION_NOT_HANDLED_M (1000007e)
This is a very common bugcheck. Usually the exception address pinpoints the driver/function that caused the problem.
Let us see what was the exception that took place -
Code:
3: kd> !error c0000005
Error code: (NTSTATUS) 0xc0000005 (3221225477) - The instruction at 0x%08lx referenced memory at 0x%08lx. The memory could not be %s.
So, according to the error, the ATI driver considered that the memory at the address is a string even though it was not. Strange, right? Well, that is why the system crashed. It might sound a little silly on the part of Operating System but well it is built to protect your data

Let's check the stack -
Code:
3: kd> knL
# Child-SP RetAddr Call Site
00 ffffd001`bdf2e360 ffffe001`fc66f080[U][B] atikmdag+[/B][/U]0xc50ab
01 ffffd001`bdf2e368 ffffd001`bdf2e3a9 0xffffe001`fc66f080
02 ffffd001`bdf2e370 00000000`00a0f68d 0xffffd001`bdf2e3a9
03 ffffd001`bdf2e378 00000000`001dbf1b 0xa0f68d
04 ffffd001`bdf2e380 ffffe001`fdca6010 0x1dbf1b
05 ffffd001`bdf2e388 fffff801`16fd44cf 0xffffe001`fdca6010
06 ffffd001`bdf2e390 ffffe001`fc6794e0 atikmdag+0x1244cf
07 ffffd001`bdf2e398 00000000`00000002 0xffffe001`fc6794e0
08 ffffd001`bdf2e3a0 00000000`00000000 0x2
And there it is! The ATI driver is the one responsible for all the mess

It is always strongly recommended to use the Graphics drivers provided by the manufacturer since they contain special tweaks. Kindly download the Display Driver Uninstaller from this
**LINK** and uninstall the currently installed ATI Driver. Once the driver has been uninstalled, please download the driver from this
**LINK** and then install it and see if the problem is solved or not.
Let me know how it goes ^_^
Regards,
Pranav