I have a VisualStudio2010 and MFC, C++ huge application that cannot be shipped, due to its complication and dimensions. In case of need, Teamviewer sessions can be done to help resolving. Program works fine in Windows32. Trying conversion on Windows64 gives problems, either in compilation or in execution. There are crashes on Child window creation, Tooltip and CreateBitmap management. First problem is described in attached files that are printscreens showing the necessary elements and debugger steps that bring to a crash, inside wincore. Other problems may be described to people that have skills to solve this kind of issues.