Hello!
1. I have a problem in Archicad 10. I can´t see the image of the the libraries in object default setting at the down left side when i choose example doors,Windows or other object.
2. I can't choose to draw example rectangular wall, there is only white(off).
I know someone who had some very strange viewing problems (similar to yours but could not see the image in the upper right hand corner), but only when his laptop was hooked to a projector. And it was not all projectors but only a specific one. You might check things like different monitors or monitor cables. I am not sure if there was ever any resolution to my friends issue but thought I would through it out there in case it might somehow be related.
I had that same exact issue when I installed AC 10 on an older PC in the office (I think it had only 256 MB RAM, and an old small resolution video card ) what are the specs of your machine?
Shared video memory is not a good idea - your card probably does not have enough OpenGL power to really do anything. Archicad is a high end software and cannot run satisfactorily on an average computer ...
Rule of a thumb: check the price tag. If close, it should be OK.