I main interface of the single thread is used after simple udp communication and computing Cchart control curve, and then there is a button can pop up another modal dialog interface, this interface has several parameters shows that still use GDI + drawing part of the curve, the GDI + to use double buffer drawing also opened a thread, interface and display parameters didn't do ~ ~ ~ ~ now the problem is the main interface used alone no problem, but the pop-up interface of another common run occasionally occur when the software automatically restart, I want to know how to deal with the two interface at the same time run? Thank you ~ ~