[PROBLEM] connecting to SMB server: "operation not permitted"

[kegepet]

system:
raspberry pi model B
Xbian 1.0 alpha 5
XBMC version 12.1
mac version: 10.8.3 (mountain lion)

Here is my problem. I have an smb share on my mac and tried connecting to it from xbian. At first, I successfully did so although it would not list any directories as I did not set the appropriate permissions. Finally, I allowed "read-only" access to "everyone" for the shared folder, and then everything worked fine. Curious as to why it did not prompt me for a username/password upon that initial connection, as it did when connecting to a share on my other raspberry pi (configured via normal smb.conf), I took away "everyone" "read-only" access and tried to change the url from "smb://MYMAC" to "smb://user@MYMAC", where "user" is the name of the owner account for the shared folder on my mac. Everything seemed to break at this point. Now, anytime I try to connect whether with or without a specific username in the url, I cannot, and instead get an error message, saying "operation not permitted". I was also able to duplicate the entire process using the ip address. At first it connected, then when I tried to add a username, everything broke and now I cannot connect at all--with or without the username. Any help would be greatly appreciated.

I should also mention that I get that same "operation not permitted" message when browsing to the system. I can access other shares in the same workgroup, namely "WORKGROUP" (as I said the samba server on my other raspberry pi, running raspbian wheezy, works fine), but not the mac.