oh sorry, copy that. thanks again!

Thanks guys.

This is a 'clipping issue' - it's well documented. Change between Perspective/Parallel Cameras to fix it. It's usually caused by having some loose geometry miles from the model's origin ? Or a component with its origin miles from its geometry. Especially noticeable in CAD imports where you have perhaps kept the origin ? Test to see what it is... Model Info > Statistics > Purge unused & Fix problems. Switch all Layers ON and View > Hidden Geometry ON If you Select All [Edit] and use Entity info it gives a count. Zoom out so you can see everything you expect to be in that selection... Now use Select with a fence holding Ctrl+Shift to remove those items from the selection. Are there still items in the Entity Info list ? Try to establish what they are. You can probably hit Delete and remove them and the clipping should stop. If you think it's a component origin issue... Model Info > Components > tick Show Component Axes... If any component-instances have issues use the context-menu to Change Axes to something more logical...

One simple way of looking at orbit and zoom control is to remember that SU uses the position of the cursor to work from. So if you start to orbit with the cursor on the object it will orbit around that point, however if you orbit with the cursor next to the object and therefore pointing at a non specific point in the distance it will orbit around that point therefore throwing your object out of view with only a small movement.