Incorrect disk usage reported for couple of virtual servers

To my surprise one of my lesser used websites are reporting a very high disk usage.

Virtualmin shows 4.09GB but when I "du" the whole home folder it shows only 4.8MB. The databases and e-mail disk usage is tiny.

Home disk space used (including sub-servers) 4.09 GB (4.09 GB by server administrator, 64 kB by mail / FTP users)

Space used by databases 2.18 MB (2.18 MB in this server, 0 bytes in sub-servers)

Total disk space used 4.09 GB

Bandwidth usage since 13/06/2009 0 bytes

[root@cp home]# du rupturedflow -hs 4.8M rupturedflow

Any clue what might be causing this?