I’m experiencing a similar issue to what’s posted here, but the suggested solution does not seem to be helping.
http://support.plugable.com/plugable/…
When everything is set up properly with my desktop (Lenovo Ideacentre K430), the system is unusable. Mouse movement is so unresponsive that I literally (and I do mean literally) can’t do anything with the system. However, when I connected the HDMI cable from my monitor directly into my video card on my desktop, bypassing the UD-3900 it is working beautifully. The mouse and keyboard are responsive, the second monitor (plugged into the UD-3900) displays correctly and acts as an extended desktop.
Prior to bypassing with the HDMI, I hooked it up to a laptop and it worked perfectly without any bypassing necessary. While this workaround is helping for the time being and does help me to use the 2nd monitor, the main purpose I bought the unit for was to be able to hook it up to my work laptop with a single cable. Having to unhook the HDMI from the desktop and plug it into the UD-3900, and then plugging the UD-3900 into my laptops USB 3.0 port is doable, but it’s an extra step/complication from what I was expecting.
Any thoughts/suggestions?