Hi,
I just got coppermine 1.3 up and running, and in the first few days a couple of the first members commented that they didn't really have enough space, so I upped the usage quota/limit, but now it would appear that it only affected members who joined after I changed the usage limit, and not those who joined before.
Any possible reasons for this?.
Make sure everyone is in the same group (check also multiple groups). There is no way it can happen as you describe. If problem persists, enable debug mode for all and post details of 2 user accounts illustrating the different quotas.