Most recently (this morning), a team lead for a group of developers came in, trying to figure out why it was broken. So we dug into the logs. It's a java app, so it uses log4j as the logger, making it nice and easy to see the problem.
Clearly, in the log file, I see a message similar to "we are creating file /application/work/datafile.xml". It is followed up with a line about it transferring the file to another location. That is followed by a stack trace, clearly showing that it failed to transfer a zero byte file "application/datafile.xml".
How did the application make it through testing? It's not even the same directory. In one instance, it's "/application/work", but in the next, it is "/application".
Do we really feel like we shouldn't test? [sigh].