Mac OS X 10.6.3 includes an updated version of Samba, which appears to be giving permissions errors when some people mounting SMB volumes. When files are copied to the SMB volume they get a “The operation can’t be completed because you don’t have permissions to access some of the items” error. Almost all of the people experiencing this issue are mounting SMB volumes hosted by NAS devices, but a few people have reported in the Apple Discussion Boards that this can happen with Windows 2008 SMB server shares too.
In most cases, this permissions error is limited to certain file extension. For example you can copy .zip files, but not .docx files. Apple is aware of the problem, but they have not commented on it. Two workarounds have surfaced. One is to always zip the files prior to copying them to the server. The other is to use the Terminal to copy the files to the server (the cp command works).