"application has been blocked from accessing graphics hardware"

I have the same problem but I am using another gpu (Nvidia Geforce GTX 675M) I did not have this problem until my windows 8.1 updated about 2 weeks ago (november 2014) 

If you find a way to solve this please reply.

Regards Jonathan

Tried all of this.  Using a gtx-650.  This didn't start occurring until I replaced my cpu from a 6 core to 8 core amd 8350.  Downgraded the nvidia drivers from the .75 to .60 with the same results.  Not sure, but either MS or Nvidia screwed the pooch here because it will work sometimes for an hour, or sometimes fail after 5 minutes or so.

This is not an AMD driver issue. I am using NVidia and have the exact same problem. Mine started when I upgraded to Windows 10. I've tried everything short of uninstalling Windows and switching to Linux. That's looking like the next step. 

I completely uninstalled (clean uninstall) and re-installed my drivers. Not the issue.

It almost seems like Microsoft changed their libraries and is preventing the drivers from using the hardware.

I can understand your frustration. Sometimes it seems everything after Windows 7 is in a state of flux. Shame because technically with their massive kernel improvements in Windows 8 and 8.1 it's actually running better on slower machines and starting faster even on non-UEFI hardware.

But this was fixed for me by manufacturer hardware and driver software, and the MS verified drivers from AMD were better than AMD's own later releases! Thank MS for testing that thoroughly before allowing it to go onto their official OS image! Also it cannot be a dead-end problem caused by the Microsoft OS else I would never have got it working either. What did the AMD forums/support say? You should really go there first.

But I'm with you on the Linux thing. Right now the new Ubuntu Trusty (14.04) Linux distribution plus Steam for Linux and free built-in free Libre Office is just as appealing (maybe more) as Windows for day-to-day work in addition to games. The only thing holding that back is the lack of cross-compiled Linux games. But the Steam OS/Steam Box is going to change that very quickly I believe!

As a last resort for Windows I would also try enabling UEFI BIOS if your graphics card is GOP (also UEFI) capable and never install any of those additional "afterburner" utilities. The AMD drivers already have boost control (PowerTune) built-in, even the base drivers provided by AMD to Microsoft (which work better for me than their stand-alone/full driver downloads and later versions). These all came from AMD not Microsoft.

This article I wrote might help with that:

http://codechief.wordpress.com/2013/02/14/how-to-setup-windows-8-in-uefi-bios-in-uefi-mode/

But one important fact to consider is that AMD's earlier submission to Microsoft is better for some people also points the finger at AMD not Microsoft. Because MS have strict testing requirements for "logo drivers" (pre-installed on OS image) AMD would have been forced to get it right when submitting for the base OS driver. But after that they've totally failed when left to their own devices. That's still not Microsoft's fault in my opinion. But that doesn't help you. Best shout more on the AMD forums than at Microsoft then.

Been a lot of inconsistency with AMD drivers for a long time now, and their updates are extremely slow and still include the old ATI brand which is not a good sign. Anyway, after a lot of experience trying to get a Litecoin mining rig with six R9 290X's running I discovered a whacky fact is the Microsoft drivers are sometimes better in 8.1 than the current AMD production or beta drivers!

Although it seems lame to advise "check and update drivers" in my experience with AMD unless you have the lucky hardware combination which nobody knows 8-) it's the norm to constantly reinstall, remove all, try again, until it works. Here are some steps which may help:

1. Temporary = Go to the system advanced options and find the part where you choose how windows updates drivers, turn off automatic search and update of drivers.
2. Run the AMD express uninstall of all components. Do not reboot yet...
3. Delete the C:\AMD folder which contains a copy of the whole driver installation source (and all the previous versions - I wish they would clean this up it's really big and gets bigger each upgrade!).
4. In Device Manager, choose the menu option "View - Show Hidden Devices".
5. Expand all audio, video and display devices and manually uninstall all HDMI audio, ATI/AMD, etc... devices. If you skipped step #1 or #3 you will fail here because after a certain point it will start reinstalling them all again getting you in a real mess (half removed/half installed) then reboot and go back to #1.
6. Delete all ATI and AMD folders from both "C:\Program Files" and "C:\Program Files (x86)" if you have 64bit Windows. You should do with your hardware spec and for all those new memory hungry games. Would affect the driver issues too, could be more or less bugs in 64bit compared to 32bit.
7. Open REGEDIT and expand Local Machine\Current Control Set\Services then delete all service keys starting "ati..." or "amd...". Also check Local Machine\Software for any ATI or AMD keys and remove.
8. Now after the next reboot you have a clean system which will NOT auto load any drivers/start in SVGA "Microsoft Basic Video Adapter" driver mode.

From this point on, you can try different routes to get a stable system (repeat ALL the above steps again to properly reset and try again!!!). Various ideas are:

1. Turn auto driver update on and ONLY install the Microsoft update driver (and older but stable redistribution of the current production driver - dated December 6th 2013). It works much better than the repackaged and released AMD driver even when it's the same version (strange but true - and that's also how you get the sixth card working on a Litecoin rig!).
2. Turn auto driver update off and manually install the current production AMD driver.
3. Same as #2 but with the latest beta driver.
4. Use the "Refresh" OS option to basically reinstall Windows keeping your data and profile.
5. Perform an upgrade install (reinstall from Windows USB/DVD) which works better than refresh.

One of those should work. Other things which could be causing trouble are incompatible tuning utilities or Hypervisors which support 3D/graphics sharing (VMware workstation).

I'd have hoped this error message would have been documented somewhere properly (MSDN usually) so we could sort this out ourselves. Before assuming it's Microsoft's fault though I'd say AMD are taking way too long to stabilize their driver platform. I prefer AMD and will continue to buy them as long as they are ahead and good at super computing (crypto-currency mining) but I must say NVidia driver releases are both much more stable and very frequent.

Generally you want this auto driver install on because it just makes plug and play much better and not having it may cause some device installs to fail or install older incompatible drivers during their setup routine. But if you need to leave it off to stay working. Then complain on the AMD forums until you can work in normal/auto-update mode again.