I've had somewhat similar issues actually, but not completely preventing the use of the camera…
The PS3Eye has this particular behavior that even if the webcam is not plugged in, it will answer as if it is and display the "No camera found" image.
Probably the issue has appeared with the auto reconnect mechanism. Your Sony Motion Eye might need a bit of time to connect (more than 1 second) such as it is initially considered "Disconnected" (Do you see this message ?), and Kinovea try to pick up the first available camera, which would be the PS3Eye.
I'll see if the reconnect mechanics can favor the camera that was actually connected.
PS: I'll delete the duplicate message in the other subforum.
PS2: I'm away from computer for the next week.
