You may want to check out www.stickyminds.com and look in their News Centre. I just had a quick look and did see one article about bank machines in Austria going down but it didn't look like it was caused by lack of testing. However, there may be something of interest for you there.
I'm sure I've also seen a site that lists serious software defects in the world but I can't find it after a quick search. Maybe someone else knows this site?