Ed01 wrote: What I don't understand is what it will do in release mode : 0(myparameters). This should crash, shouldn't it ? Or maybe there's something I missed in #define principle The function gets called the same in release mode as it is in debug mode. The only difference is that the body of the function is "missing" in debug mode. "Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

I have not designed an application that processes data in a time interval of unver 1000 ms. a time queue timer is one solution for For processs that work in the 500+ ms range. For anything shorter, I recommend a separate worker thread and WaitForSingleObject(). Kuphryn

thanks, I won a lot of time... For anyone who has the same problem, you just have to add AfxEnableControlContainer(); at the beginning of the InitInstance() function in your App class ! :-D