Whenever I call ChoosePixelFormat, a new thread is created, and that thread uses 50% of my CPU non-stop until I shut down the program (It would probably be using 99% of my CPU if I didn't have a dual core setup). This mystery thread makes function calls to nvoglnt.dll. I do NOT have this application explicitly linked with any OpenGL libraries, and it happens whether or not I include PFD_SUPPORT_OPENGL in my pixel format descriptor. The application having the problem is a standalone bare-bones dialog application, created by the IDE, and modified by me only with respect to adding ChoosePixelFormat, so I don't believe it's something I'm doing wrong. No matter what settings I use for my PIXELFORMATDESCRIPTOR, I always get the problem. Here are the specs on the system this happens on, running Windows XP: AMD Athlon 64 X2 4400+ 2.2Ghz Dual-Core 2x1MB L2 Cache Socket 939 64-bit CPU EVGA GeForce 7800 GT PCI Express 256 MB DDR3 Video Card ASUS A8N32-SLI Deluxe Socket 939 NVIDIA nForce4 SLI X16 ATX AMD Motherboard This does NOT happen on either of my other two computers. Their respective specs in summary are: 1. Dell Inspiron 8500 w/ Intel Pentium 4M, ATI Radeon 9000, Windows XP 2. Pentium 4 2.4 Ghz, GeForce 3, Windows 2000 Has anyone else had this experience? If so, can you give me any suggestions on how to resolve it?