I totaly forgot about that thread...
Anyways, it is/was a problem with OpenConvo itself, not with the Windows DLL. Wouter has send me an updated exe that seems to work correct again.
He said to me that he's going to release an update soon, including an installer, so let's wait for that...
All I can say about it, is that it works again very nicely. (Although, personaly, I liked the older toast-display (plus-toasts) better then the current fading one). Anyways, thx again Wouter...