Upgrading via the WPMU Dev Dashboard Plugin fails

When I attempted to update the e-Newsletter plugin via the WPMU Dev Dashboard I get the following error:

Unpacking the update…

The package could not be installed. PCLZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature

NOTE: It did successfully update the Avatars plugin, so I’m thinking it’s not my system.