Assembly shifted to one side of screen

Hi,

I have an assembly of mine comsisting of two enclousres filled with a variety of parts.  About 3 levels back of the final assembly, the entire assembly is moved to the left side of the screen when I click "Zoom to Fit."  So, each assembly that calls in this subassembly is also shifted to the left.  There is nothing to the right of the assembly that I can click to get rid of.  Please let me know if you have any advice.  Thank you.

SolidworksAssemblies