Bug error

I have coded a tab control using property sheets. After compiling and executing the program, I attempt to close the program. After closing the program, I always receive the error message "Debug Assertion Failed. File dlgprop.cpp. MFC42d.DLL error." Could someone please help me. Help is appreciated.
Thanks,
Jason

This was the code that gave me that error


((CMainFrame*)GetParentFrame())->PostMessage(WM_CLOSE)