There might be (many) bugs in the zip upload code as I haven’t tested it at all, just wrote it up

..but the line number that your error message show is before the zip related code, so it’s not that.. The code that the error comes with is:
Line: 254. This should move the uploaded file to the assets/galleries/docid/ folder, eg. assets/galleries/docid/something.zip
move_uploaded_file( $_FILES[’file’.$i][’tmp_name’] , $path_to_gal.$name );
Line: 255. This should then chmod the file. But it seems that the zip was never moved there by move_uploaded_file. Don’t know what’s that about.
chmod($path_to_gal.$name,0666);
Its not the chmod that is failing, it works fine even on windows, it’s the move_uploaded_file that’s not working.
Unfortunately, I’m just leaving for a work trip for the rest of the year and won’t be able to develop this as much as I’d like. I hope I get laptop soon what I can use in the mean time.. But there might be some lag in my responses for a while.