Connecting to mailserver: "QWaitCondition: Destroyed while threads are still waiting"

I've got a problem with my application, which I want to download mails from the given mailbox. When it turns to connecting to the Internet, it shows me such an application communicate (it's unimportant wether or not it succesfully connects):
"QWaitCondition: Destroyed while threads are still waiting"
What does it mean?
While I was building my application, I studied this app, downloaded from qt-apps.org. The same problem exists here - I configured it in the .xml file and ran it using windows console (adding the path to .xml file as an argument) but after that, I was given the same communicate.

Could you help me? Maybe you could download that program from the link above and try to run it? Thx in advance. :)