Yesterday evening I got a call from our maintenance team on the attendance phone (I'm responsible this week).
A customer had problems with our product.
After some initial investigation (all by phone, because I wasn't at home) it was clear that it was a problem with the database (of course *sigh*).
We fixed the problem within 15 minutes. To my own surprise I knew enough of the database interna to tell him what cause lead to which problems and where to look for further informations.
It was somehow the customers own fault. He has some problems in his network which we have told him for months now, but the customer had no time (or didn't care which I think is a better cause) to fix it.
Well, now it has been communicated over official lines and I hope, they fix their problems faster now.