This document describes how the small Dutch bank 'van der Hoop' went broke while being supervised. Van der Hoop was actually a small niche bank with 'rich' customers.
The case goes to show that supervision is never a guarantee for your funds. Furthermore the Dutch central bank (which is also the supervisor of banks) is quite embarrassed of course. And will undoubtedly step up its supervisory efforts even more.
As a final touch of irony, the Hoop in the name 'van der Hoop', means hope.
Well, there's little of that left for the customers that held more funds/deposits than the 20.000 euro of the Dutch Deposit Guarantee System.