When attempting to set the mouse's cooperative level to foreground/nonexclusive DirectInput has suddenly started always returning E_NOTIMPL. This an error code for nonimplemented functionality. This error is not application specific. My pre-existing projects are all facing this problem, as are the DirectX sample programs. This also occurs when using background/nonexclusive. It is possible to use exclusive cooperative levels, but that is inappropriate for my current project. I have never run into this error before and am completely at a loss for a solution or even cause. I seriously love it when base level functions in a mature library return error codes stating they are not implemented yet. Any ideas here? Google showed several people running into similar issues, but without decent resolution.

Some interesting stuff to report. I decided to see if the error may have been fixed in the December update to the SDK. I was using the summer update. Well, it wasn't but I am receiving debug output now ( which I was not receiving in the Summer update ).

I tested my problem using the December update mouse sample program. The debug message "DINPUT8: Mouse::Acquire: Non-exclusive mode not supported" is now asynchronously output after trying to use a nonexclusive mode with the mouse. I also noticed that the December update got rid of the managed "Scrawl" sample, which was a demo using nonexclusive mouse access.

I find it very difficult to believe that this is 'correct' behavior now, though. I have not heard any mention of Microsoft phasing out nonexclusive mouse access, and surely I wasn't the only person using it - and confused by the immediate change.

Can somebody else with SP2 and an updated system verify that nonexclusive mouse access is no longer allowed? I am going to reboot my machine now and see if there is some inexplicit change in behavior.

After rebooting the problem has disappeared. This is extremely annoying. I wonder why it was failing before. ARGH..

Thanks in any case.