Cubase6+Win7 64bit+RadeonX550 graphics - Video window is black - Why!??

[jouleskeys]

I am using Cubase 6.0.7 (32bit/64bit) on a Windows 7 64bit system with a Radeon X550 Graphics card with 2 screens - XVGA and VGA (analog/digital) and a Digi003 Firewire 400.

As directed by Steinberg, if it works in Quicktime, it should work in Cubase. Quicktime is freshly installed, and the video plays there and in WMP with no issues, but not in Cubase 6. I have converted the file types over to .mov , .avi , n264 , jpg , .mp4 in an attempt to get them to run in C6; though with no luck at all.
These files run perfectly with Sony Vegas, though not in Steinberg products. Customer support is useless!

The strange thing is that I can see the video strip with frames, and when I double click it to bring up the video window, the video can be seen in the video window for a millisecond or so, then it suddenly turns black and vanishes.

So, there's a few things that could be the issue though I have no idea what it could be:
1/ 64bit system + C6 + QT (32bit) = No Cubase6 video?!? Though according to Steinberg it should be fine
2/ The graphics card is not tested by Steinberg = not compatible..!?!
3/ Lack of codec or link between QT and Cubase.

A few moments ago, I tried in install "K-Lite Codec", though errors came up. Not sure why.

Apart from video in cubase, the system is solid and I do not use it online to avoid issues.
Thanks for your help on this as I know you are all very busy , though really need this fixed as I have an important video project to do asap for a client.

[jouleskeys]

This is fixed having got a new Graphics card. The X550 is simply too old to cope with all the new codecs etc.

I have bought an Asus GT550 Silent 1GB DDR3, and everything now works