i have an assembly that looks very choppy.  when i rotate the view the whole model dissappears.  the only way to get it back is select a part in assembly tree and zoom to selection.  if i open a part or sub-assembly from this top level assembly, the parts and sub-assembly are normal!  we have tried this on several different computers with the same result.  can not work with it at all.  any suggestions???  graphics driver is Soldworks approved!  all other models work fine on computers.

Windows 7 64 byte,  Solidworks 11 SP. 5.0