OpenSUSE Install :: Try To Boot But The Screen Goes Off - Works With Failsafe Mode?

I've got this really huge problem, which I really want to solve, because otherwise I might even switch back to ubuntu. So here we go. Yesterday, I had a problem with mounting nfts hard drives and solved (you guys solved it actually) it by adding ntfs to the /etc/filesystems file. (I doubt, that it has anything to with that, but it might, so I will just tell you everything I did) I added an ATI driver repository as well, which is probably the key to this problem.(or at least something with drivers) --> not sure if I installed anything

So however, the problem is now, that the screen tells me, the signal would die just before the log in screen appears. ("No signal" --> screen goes to standby --> can't wake it up again--> no opensuse for me) I'm now running the system in some sort of safe mode and it works, but I think, that it is using my on board graphic card and not the actual "radeon hd 5600", which provides much better quality. just looked it up, yes it is using the crappy one (on board) So here's the question: First of all why does this error occur(worked fine before) and secondly how can I fix it?