Inspiron 15R 7520 : AMD video card keeps messing up

Hi,

I just bought a Dell Inspiron 15R Special Edition. I got myself the i7 version.

TLDR VERSION:

Every time I try to launch an application using my video card, my screen would black out and I would get back to the login screen. Applications such as games, steam, catalyst center... force close on Windows startup and cannot be launched after (nothing happens). All of my drivers are up to date, clean reinstall already done several times. Any extra tips?

LONG VERSION:

Typically when I got the computer I went into my standard "laptop installation procedure", which is basically:

1. Make sure every security-related software is up and running (ie. antivirus, firewall)
2. Download Firefox as my standard web browser, + basic Firefox extensions such as AdBlock
3. Get my system up to date by downloading the latest version for each and every of my drivers: BIOS, video cards... So yes, before you tell me to kindly install the last drivers, I already got them installed, using the Dell website to see what should I have to update. Got my Catalyst center updated too
4. Download Steam and test my PC performance with a game (in this case, I used Rochard and GTA IV)

The three first steps were, as usual, cleanly done. When I got to the fourth step, first problem I had was: Rochard was seemingly running on the HD Graphics and not the Radeon, hence very laggy. No problem, I fixed it by changing the parameters in Switchable Graphics and it worked fine. Then, GTA IV worked directly without any problem.

At this point, I thought I was good to go. Until I randomly went browsing on Youtube, and I saw that Firefox was absolutely unable to display any Youtube video. The video would not appear, and my cursor would change for half a second to a "loading" cursor, and then go back 2 seconds to a normal cursor, back to loading again... At this point I believed I had a video card problem?

I then launched the "My Dell" Application to run a complete check up and oh! The splash screen appears, but then, nothing, the application just completely shuts down. I then tried to use Youtube on Internet Explorer, the video was displayed fine, but after like 10 seconds of video, my screen would flash on and off for about 30 seconds, and then I'm back to the Windows 8 Login screen, with Windows seemingly restarted since logging me in would not show what I was running before the crash. At this point, every time I would start Windows, my Steam would force close, and the Catalyst control center too.

(note: a couple of forum posts exposed the same problem, for example: http://en.community.dell.com/support-forums/laptop/f/3519/p/19514226/20401009.aspx , so I believe I'm not the only one to have this problem. I originally thought that I got unlucky and got a faulty laptop, but now I'm not so sure...)

So I tried everything I could find, out of my own knowledge and out of all these forums. I uninstalled the Catalyst center, went to the device manager and uninstalled both video cards drivers. Rebooted the PC, installed the drivers, tried to launch a Youtube video... Same crash. This time, I couldn't set my screen brightness anymore, and Windows would tell me that it deactivated my Radeon card because it had problems. And I had to reinstall all over again to be able to gain control of my brightness again

Still unable to launch a MyDell instance for a checkup, I tried the pre-boot complete tests, left my computer a couple of hours running them, and each and every test passed without any problem, but I still have the same problem.

So here I am now. I tried everything I could do: having the latest, up to date drivers, clean reinstall of the graphics card + switchable graphics app... But still the same problem: my firefox is unable to show any Youtube video, while my Chrome and Internet Explorer can play tehm for 10 seconds before the crash. Any attempt of me launching an application using te video card (such as Steam, or any game, or even the MyDell application) is a failure: I would usually have the splash screen, and then nothing (not even an error message).

So... I know that usually, and Intel graphic card + AMD video card do not make quite the good couple. But I would expect it to work at least for basic tasks such as watching a video. What is it that I could do - aside from the traditional "please update all of your drivers" - to finally make this work? Is my laptop actually faulty and then should I send it to be repaired?

Thank you