Hey there Youngblood,
I know the game crashing like this is not a fun thing to deal with. I do hope the main thread suggested above helps.
From our end, I am forced to start with informing you this system is below the requirements for Diablo 3. The Video card may not be able to keep up with the game and only the recent patch or a PC change is causing the problem.
Here is your card next to the required one.
On that note, as you crash 90 minutes or so in, I would check the state of the hardware on the system. You can do this with an HWmonitor. I would check your Temps to make sure nothing is getting to hot.
I hope this information helps!
/Nathardrick