I had the exact same thing happen with my then new Stainless Steel roller cabinet and it was totally full. I was pushing it back into the shop up the approach incline and it went over.
Well....at least I found some of the small tools I thought I'd lost. *^%(*#%!! Grrrr. The worst of it was it put some bends and dents in my brand new shiny toolbox.
I guess it may be more of a common occurance than I thought.
