I am seeing this sporadic behavior when users press the "Install All" button, is that what occurred? If you restart those machines entirely then just pick one of the smaller libraries on its own, does it download or get stuck queued?
The "Install All" button got me a similar fail as Matt.
For three libraries listed, the first one showed some activity
that never went anywhere. It never really started the d/l.
The other two libraries showed "Queued".
I force quit the manager, rebooted and d/l'd them one by one and it worked fine that way. jadp.