Hooking specific instances of firefox.exe fails

[kunom]

I try to hook the main process instance of "firefox.exe". It fails, for unclear reasons, for the second process. Here is my trace log, you can see the command line and the two agent loads. The second one fails:

Error 0x8007001 points to ERROR_INVALID_FUNCTION, which I don't understand.

When writing the debug logs to the file, the following is logged:

Error 0x80070002 (note the different number to above) indicates ERROR_FILE_NOT_FOUND, which I also don't understand.

Looking at TransportEngine::ConnectAgent and EngErrorCodes.h sort of indicates that CNktDvTransportEngine::CConnection::Initialize fails with that error code.