Im working with directshow, and the app is multithreaded, and it runs inconsistently. I noticed that I'm using CoInitialize, and that a CoInitializeEx is available which has a multithreaded option, and that sounded like it could get me better thread control for fixing the instabilities in the app. However upon attempting to use CoInitializeEx I get a compiler error for undefined symbol. has anyone ever seen this before? know how to fix it? I know the definition is in the included .h files because I searched and found it, but the compiler doesn't recognize it. It makes no sense because the CoInitialize and CoInitializeEx defs are right next to each other, and CoInitialize works! it's driving me nuts!