with the X1 to help with docking it everyday at the office I have a USB Port replicator with digital video. I am not using the digital video but the USB ports, head phone and mics plus ethernet.
When I plug it in it detects it OK, I then installed the software. But after reboot it looks to stall when logging into windows, screen flickers back and forth and locks up the operating system. I unlplug it and reboot and window is working fine.
Note as I mentioned I am not using the digital output but instead using an external monitor via the display port on the back of the laptop.
Also its is very slow to boot (Lenovo bios splash screen is there for about a minute)
I have gone into the bios and turned off all other bootable devices just leaving the laptops hard drive.
As a work around I have removed the software and I am getting the basic functionality of the port replicator, but not the ethernet.
I have run the update manager but does not appear to show a need to update the drivers.