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 :-
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 -
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
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.
Let's check the stack -
And there it is! The ATI driver is the one responsible for all the mess
3: kd> knL
# Child-SP RetAddr Call Site
00 ffffd001`bdf2e360 ffffe001`fc66f080 atikmdag+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
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 ^_^