In Lightroom 5, when attempting to "Reset (Adobe)" in the Develop module (by holding down Shift) a "stack overflow" error appears. This is reproducible every time one attempts this.
In develop module, when an image with an older process model (in this case 2003, but seems to be on all) is displayed, shift-click the RESET button and an error window is displayed, "An internal error has occurred. ?:0 stack overflow". Pressing Ok dismisses the error box clears and the process model is unchanged.