Ok, if you don't see the healthbar/mouse, or any other "2d" graphics such as hitting tab to look at your inventory/quests/etc then it's a different problem than what most people are getting- and if alt-ctrl-del isn't tabbing you out and opening the task manager (I'm assuming Windows XP of some flavor) then you probably do have some sort of hardware issue, but of course I can't be 100% about that. I would try swapping out your video card if you have another compatible one handy and see if that resolves the issue.
I also noticed you have an ASUS board- now don't go changing all your settings willy nilly, but I had to go over every one of the settings on my A8N32-SLi Deluxe and set them to manual because ASUS likes to overclock by default. They have a real thing for upping voltages without saying anything, so 1.3v becomes 1.35v on your Vcore for instance... So you might want to check all the stuff in your bios against stock settings. (cheaper than buying a videocard to find out that's not the issue) Of course using a driver cleaner and doing a reinstall of your chipset/graphics card drivers might help also.
You can also google "nvtemplogger" and get a little program that I've found tremendously helpful in pinpointing heat issues with my GPU; it writes a log to a text file of your core and ambient(if available) temps every 15 seconds or so, if it's heat you can open the file after you have crashed and see if that's the problem. ( actually, come to think of it- You say you restart your machine a few times then it suddenly seems to work? That sounds like it's cooling off perhaps, and works when it goes below a certain threshold? )
Of course using a driver cleaner and doing a reinstall of your chipset/graphics card drivers might help also.
Just grasping at straws really, but those are the top few ideas that come to mind. I really do hope you can get this sorted out- I know how much it stinks to worry about having to replace expensive components. (Currently worried about my processor, myself. *sigh*)
**disclaimer: I've been awake a long, long time.
