Assembly Model Automatically Zooms Very Far Out

Hi,

I have an assembly that all of a sudden started zooming way out when I click the isometric view or try to rotate the whole model.  It zooms so far out that I cannot even see the model anymore.  I can zoom back in to where I can see it again but the moment I try to rotate it, the model disappears again.  It started happening just after I added and then deleted a couple of conflicting mates.  Anyone seen this before and know what to do about it? 

Thanks,

Jeff

SolidworksAssemblies