I'm having a problem with the 3D view in Hammer. If I just have started a map, or am changing the view from 2D to 3D, the 3D view is not rendered - it just goes black, and when I rotate, nothing happens, just remains black. It only happens when I start a new map or as I said, change views to 3D. The only way around it I have found is to select a brush in 2D, then go Tools > Center 3D view on Selection, this seems to "wake-up" the 3D view and get it rendering. What on earth is going on here?