I'm using Ubuntu 12.04 on a lenovo T430s. When using an external keyboard with track-point, I observed the following unexpected behavior: when scrolling (pressing and holding the middle mouse button and moving the track-point), the text I had selected last is being pasted. But this should only happen when clicking (not holding) the middle mouse button. The interesting thing is that this is only happening on the external keyboard, the the keyboard of the laptop is behaving correctly. Furthermore, this is only happening when the track-point is used shortly after pressing the middle mouse button, it is not pasting when I wait for at least a second.
Googling didn't bring up anything. Are there any similar experiences or a workaround I missed?
One acceptable workaround for me would be to disable the middle-button-paste on the external keyboard only, so that I can still use an external mouse to do the pasting. I only found a way to disable this feature completely on all devices, but I use this pasting feature quite and often so I cannot live without it.