Hi: I was running my code and everything seems alright until the process gets to this line: g_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET|D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB(0,0,255), 1.0f, 0 ); It was not any kind of error that poped up. Instead, VC++6 gave me a hint on a message box : "User Breakpoint called from code at 0x77f7570". The result is the same as as if I have added a breakpoint somewhere where the program stops at, and when I continue executing, everything is normal except every time, the execution pauses at the same line of code and gives out the same message. Has anyone before ever encountered so weird problem like this one? I need help on it pliz.... Thanks for your hlp in advance