Just where is the LifeCam software? Aha .. you have to download them from Microsoft. This can also be found fairly quickly.
For Windows 8.1, there is the LifeCam software in the version 4.25. This can also install clean, but unfortunately it does not start.
As it turned out probably have this problem with other people. And be the answer to that one is to install the older version 3.60, which was released for Windows 7 64bit.
So again deleted all the drivers and uninstall the software ... then tested with the old version .. and already working the LifeCam software. As far as ever super .. BUT: You can not record in 720p resolution.
Recording starts briefly and then freezes after a few milliseconds.
For my taste, it's too many problems that I did not expect. Therefore only 3 stars ..