Radecon I would guess the issue IS caused by your graphics card, since it's clearly not rendering objects properly: sometimes just the trees, sometimes everything. The first screenshot also shows some tiny dots that are often associated with a VRAM issue. That's not conclusive, just highly suggestive.
Anyway, if you'd still like help, please provide a dxdiag. Click Windows key-R, enter dxdiag in the run box, wait for the scan to finish, click "Save all information," and save the file to your desktop. From there, you can attach it to a reply using the paper clip (Attachment) icon included with the other formatting buttons.
