Thanks for your reply, but the answer is we're not "starting off". This is a product that has been sold for several years. There is no reason why a D3D9 application should not work on Windows 10... when the same application works fine in 8.1, etc. To redesign this product for D3D11 would take serious time, considering the development, testing and deployment cycles. This is NOT a simple D3D9 app... it's a complex application comprising 10000s of lines of codes and which is used in environment which demands high reliability. The port might be appropriate for a student project, but not the best path for this project. TwangGuru www.twangguru.com

JStrings wrote: it does NOT work with the project that I'm working ... the problem probably has to do with a) the size of the program; or b) the number of times the project has been imported In that case there is probably something (or things) in the project that requires correcting, before it causes more problems in the future. Use the best guess