[Qt-creator] undefined reference to vtable for <Class Name>

[Alexandre Beber]

I created a project and 2 classes extending QTcpServer and QTcpSocket.
When building i was getting this message - undefined reference to
vtable for <Class Name> - pointing to all the constructors/destructors
of my 2 classes.
To solve it i deleted all the "Makefile" inside the project's folder.
Actually i don't know exacly what is causing this error, seems like
it's something with the moc files. Got the hint to solve it from here:
http://lists.trolltech.com/qt-interest/2007-06/thread01171-0.html