Graphics after isolate

Often after exiting Isolate on a large assembly the graphics come back as shown attached. Solidworks believes the parts are in the right place evrything returns to normal with a rebuild but not a redraw. Has anyone else seen this?

Thanks

JF

SW2012 x 64  SP5

System Manufacturer: Other (not a known system vendor) (actually it is an HP with a 6 core AMD processor)
System Model: Other
Card Manufacturer: ATI Technologies
Card Model: FirePro V4800
Your Current Driver: 8.83.5.4
Diagnostic Results: Your graphics card is supported and the driver is up to date.

SolidworksGeneral