Comment 94 for bug 286828

Andrew: I'm no Ubuntu dev but I've been suffering this bug when first appeared and the bug is clearly and without any doubt on the Samba server side. With Samba server I don't mean upstream Samba code but the Samba server present for example in Debian Etch (and other OS/devices too, like your NAS).
The bug is not in the client side, so no Ubuntu fault here. Why Hardy was working and Intrepid/Jaunty aren't without the nodfs option? Simply because THE KERNEL HAS BEEN UPDATED. Ubuntu even backported new changes (the nodfs option) which could be used as workaround for people experiencing the bug in older versions

So, before ranting, go read all the previous comments.
Long story short: in your smbmount command pass the nodfs option by mean of the -o switch

smbmount '\\192.168.1.2\public' /home/andrew/naspublic -o guest,nodfs

should work with Ubuntu >= Intrepid