The problem occurs with 7-zip files made with 7zX 1.7.1 (Compression Level Ultra, no password, no other settings) for MacOSX.

If files are compressed in a folder (folder is compressed), the Unarchiver (2.0 beta 4) cannot uncompress the folder, but 7zX can.

With the Unarchiver, the process starts, but no folder is created.

Free files uncompress properly but have the above mentioned permissions error (User has no read or write privileges).

I'm not sure if this is a problem with 7zX or the Unarchiver.

Test file: http://www.mediafire.com/?ydjgz2k2zgn