No NAS access from non-domain-member PC

Yes it does. I believe the problem *may* have been related to me messing around with some Internet Expolorer Security settings. Specifically the setting for Local Intranet and Trusted Sites auto-logon. I may have had the option set to use the current logged on user's credentials to access sites in those zones. Off the top of my head those were the only settings I was messing around with at the time. I don't know if those settings affect Windows Explorer but I wouldn't put it past Microsoft. I'm thinking that because the logon credentials on that computer are not domain credentials, and that share is locked down to Active Directory users, the computer was trying to connect to the share using non-domain credentials and getting denied. That's just a guess though.