TextOut() - "invalid null pointer"

I've written a program in C++ which is displaying a white window.

Furthermore I'm displaying a text in the window. To accomplish this purpose,

I use the TextOut()-Function. It's working,

but besides the displayed sentence, the following is displayed:

invalid null pointer (__onexitbegin != NULL && __onexitend != NULL)||(__onexitbegin == NULL && __onexitend == NULL)

After this error there are lots of chinese signs.

I researched on the internet but havn't found anything useful yet.

This is the code I'm using to display the text:

const wchar_t* string = L"This is a test.";
hdc = BeginPaint(hwnd, &ps);
TextOut(hdc, 0, 0, string, 500); //the length is just for test purpose
EndPaint(hwnd, &ps);

Thank you for your advice.