Ok, went away to experiment a little and opened an old drawing in X1. The units were pixels with 5 sub divisions and snapping worked fine. When I changed the units in the old drawing to centimeters with 10 sub divisions snapping no longer worked. I hope it's not just me, but it certainly seems to be the case that snapping is a bit wonkey on my machine.
On the other hand it's not the end of the world as I usually turn it off anyway and other benfits outweigh this slight possible glich.

derek