i've got an exact problem, would you please kindly share your resolution to me?
Started your own thread.
See pages 57-60 of the P2418HZ User's Guide. It explains that you should actually disable the laptop webcam prior to using the P2418HZ webcam.
"If you want to set up the monitor webcam as default setting, you need disable the notebook built-in webcam"
Then, when you disconnect the P2418HZ from the laptop, simply re-enable the laptop webcam for stand alone usage.
For my notes, send me via Private Message the monitor service tag number.