I'm encountering this error when I'm running my DirectX10 program in debug mode:
D3D10: WARNING: ID3D10Buffer::SetPrivateData: Existing private data of same name with different size found! [ STATE_SETTING WARNING #55: SETPRIVATEDATA_CHANGINGPARAMS ]
I'm trying to make the project highly OOP as a learning exercise, so there's a chance that this may be occurring, but is there a way to get some more details?
What other data are you looking for or interested in?
The warning is pretty clear about what is going on, but if you want to hunt down a bit more data, there may be a few things to try.
Try calling ID3D10Buffer::GetPrivateData with the same name or do some other check to see if there is data with that name already, and if so, what the contents are. Print your results to a file, output window, or console. This may be combined with breakpoints to see where the duplicate is occurring (break when there's already data).
You may (not positive) be able to set the D3D runtimes to debug mode and to break on warnings (not sure if it can do warnings or just errors). Debug your app in VS or your preferred debugger, and when the warning is shown, it will break and you can look at the parameters.
Go through your code and track down all calls to ID3D10Buffer::SetPrivateData and look to see if there are any obvious duplicates. If there are, work up the program flow and see why and what you can do about them (this may work best after you use one of the former methods to know where to start).
How are your data names set up, and what is the buffer used for? Examining one or both may lead you to a conflict somewhere.
You may also try unicorns, they've been known to help with this kind of problem.