From the info provided, it appears to me that Tony is trying to move the mesh to the origin 0,0,0.
If that's the case then Silo can save .stl files but can't open them.

If you have Rhino you can open & re-position the mesh or re-save as STL file using ExportWithOrigin.

Or get the free Rhino evaluation version which has 25 saves.

EDIT:

Seems you have your answer here: http://www.vectric.com/forum/viewtopic.php?f=12&t=14173

Have you tried this? That would be the simplest way if it works.