[yial]

I had an issue like this once installing windows 2000. If you didn’t move the mouse during the installation, it would hang and fail. Finally got it to install by sitting there moving the mouse.

[dijit]

Wow, I had that exact same issue before.

I wonder what the cause is/was.

I'm aware that old PS/2 connectors would interrupt, vs being polled like USB.

[ahartmetz]

USB only polls at the USB protocol level - it signals activity to the host with interrupts like a normal person^W device.