Cant download ZIP file for some clients

On some of my clients I can download ZIP file of entire folder. On others it starts to download and fails immediately. What could be the cause of this.

can you restore the backups for these same files/clients? maybe you have a permissions problem.

As i remember there s a zip size limitation. Search the forums, i think it has been fixed in some version.
Else, you can restore from the client, without using a zip file.