Disk quotas not functioning correctly

One of my clients is complaining that they can not ftp new files to the server as they get a "Quota exceeded" error message. The quota is set as follows

Total server quota: 50MB
Server administrator's quota: 50MB

I have tried for myself and get the following error

> Netout: Software caused connection abort
552 Transfer aborted. Disk quota exceeded
ftp: 2818005 bytes sent in 188.72Seconds 14.93Kbytes/sec.

Virtualmin reports the following figures in the server details page

Space used by mail users 0 bytes on /
Space used by Unix user 4096 bytes on /
Space used by databases 8192 bytes

However if i change to the virtual servers home directory and run `du -sh .` i get the following

> du -sh .
572K .

If i set the server to "unlimited" quota then everything works as expected.

This virtual server was restored from a backup file recently.

Closed (fixed)