When I try to download a zip file with the plugin manager I get the following error message:
Fatal error: Cannot redeclare class zip in C:\xampp\htdocs\dokuwiki\lib\plugins\plugin\inc\zip.lib.php on line 13
I didn't find where the other zip class was declared (I searched the whole document root but found no class declaration, I called get_included_files and get_required_files but all files were from the dokuwiki directory).
I'm using dokuwiki on a plain XAMPP installation (version 1.5.3a) on Windows 2000.
See also the discussion on http://wiki.splitbrain.org/plugin:plugin_manager
The easiest fix would be to rename the class.