Doesn't Windows assign a 169 address when it can't actually get a "good" address from DHCP? I think you really need to use a different IP range.
Another thing, did you say you're using a wireless adapter for internet and a wired adapter to only access the NAS? If that's the case, I've had times where the adapters come up in the wrong order and one doesn't work. I would disable the wireless adapter and try to access the NAS. What happens is Windows looks for the NAS over the wireless adapter and of course it won't find it there.