Are you sure you are pinging the right machine? Access rights are checked? Did you check the path to whatever you are trying to get to? Could be tons of different issues even if you can ping the right machine.
in case if you still aren't able to access the folder, you should set the permission for your account under the share tab, as well as security tab. For certain occasions, if you add it only in the security tab, users will be ableto access the folders, some will need you to enter the sharing tab, share option and input your login id. Please check if you have done that.