Have tried using just the address: Kentfield, California, USA - and can't seem to reproduce your problem. My results are Here.
Perhaps it would be worth trying from scratch on a clean page (again using just the address) to see if you get a valid map in all browsers. For the record, I seem to have to set the 'map.setZoom(N);' each time I implement a google map if I want anything but the default (fairly close-up) zoom level.
It works in both browsers by setting the zoom on the set center function. The problem, as I mentioned, is I didn't see anything about that in the help or instructions. The How To online doesn't mention this at all but only mentions using "map.setZoom(N);" which for some reason wasn't working in IE for me.
Strange that you need to use 'map.setZoom(N);' while for me it wasn't working correctly cross-browser.
But it seems to be working now, which is good.