T61 + Win7 64-bit + Advanced dock, undocking worries

[CP-Geek]

Got a well working good old T61 (6460-EBG) with SSD & 8Gb memory, using Win7 64-bit very happily for ages. Started using my advanced docking-station again after a long time, but encountered an annoying error. Can't undock tha [censored] thing.

Connected to dock: USB-keyboard & USB-mouse, display through DVI.

Using the dock's eject button results in error on screen "Cannot undock, computer using devices," something about HID which would suggest to USB-attached keyb or mouse?
After searching forums there was an hint to install Easy Eject util for vista, util installs but error remains.
So, I have to jerk my dear t61 off dock, sometimes this results in freeze, sometimes not.

Of course one solution is to shut down comp but that's not the answer here. Any ideas?