on second thought... read the last paragraph first.
This could be related to my issue with the touchpad. The hardware ID for the pad is the exact same one as the one for a PS/2 mouse. I have been burned in OS deployments where the PnPID ended up loading Synaptic Touchpad software on a machine that had only a PS/2 mouse (had to create logic in my OS build script to use machine ID as a range of laptops before it would make that directory and driver available).
Have you tried a different USB mouse? You could be in double damage mode with an off brand that is ALSO using the same PS/2 ID. How, I could not guess considering it is through the USB controller. But dang, I have seen some really dumb driver stuff in the past.
Do you have a keyboard soft switch on that Thinkpad to disable the J point or touchpad?
Of course, that does not solve the USB keyboard... I wonder also if turning on Legacy USB in the BIOS might be your cure. Try that first.