i am working in autocad 2009, i have inserted a 3D model as an Xref, when i then add leaders and dimensions on my paperspace view using viewports to see the model, it either makes my drawing border in the paperspace view dissapear, or makes it so that i cant edit dimensions or leaders and when i try the disapear.

im confused!!!!!!!!!!

although they disapear they are still there i just cant see them, and they plot out fine!!

any ideas???

I know I'm probably not much help but I know exactly what you are talking about and I don't know how to fix it. This is what I've had to end up doing before. It's a real pain but it works. Render the drawing without the text and import the jpeg into MS Paint or something similar and add your leader lines and text there. I've had to do that few a times. Good luck.

If I understand the problem, perhaps you would solve it with DRAWORDER. I guess you know the command. If you don´t, type the command, then select the desired object/-s (in this case, the Xref) and when you are asked for the location, send it "Below" or "Behind".
I hope it works

Your problem is not a big deal, but sometimes gets annoying. Try to zoom in and zoom out, it will regenerate the drawing. Or re-scale your drawing. Try to add your dimensions in model space also. but if you are rendering, then put your dimensions in paper space.hope it helps you...cheers 

please check your layers freeze is on or off if its on try with DIMSTYLE leader size and arrow size may be its not matching with your paper space scale.