Hi Uwe,
I've spent a bit of time looking thought the debug window and yes, the crash is due to the Assert statement. CreateCompatibleDC is some sort of memory management function, so I can only assume that it cannot allocate the memory for the device.

I dont know why it cant allocate the memory though, because according to my memory gauge there is loads left.

Do you think that this is a Qt problem? Or a windows problem? Its obviously not something to do with Qwt (How could I ever think it was!) but I am an open source user, and hence have no service contract. Shall I attempt to report a bug?

Cheers,
Phil