[Owncloud] Problem with Calendar on new owncloud 4.5.7 installation

[Chris Green]

I have just installed owncloud 4.5.7 (from the suse repository) on my
Xubuntu 12.10 system.

It all appears to be working OK except that when I click on the calendar
link no calendar appears.  It's got the Week, Month, List and other
links across the top and two scroll bars below (very short vertical one)
but nothing in the middle.

I had previously installed (and then purged) version 4.0.8 from the
Ubuntu repository and that worked OK, i.e. I did get to see a calendar.

What might be wrong?

-- 
Chris Green