Stange USB hang when I login

More a bug report but I get this when I login. Where the Device manager for the USB just hangs and never presents the option to allow my mouse. This is happening in the most recent version. I had to roll back in the Xen options and it stopped. I am going to try again and see if I get a different result.

I have seen on several occasions;

If I plugged in the USB during the moments when the computer was powering up (T-480) the mouse pointer(s) might freeze. Not move at all. Not click at all.

If I plugged in the USB mouse before I started the power up, no hang.
If I waited until the computer was fully up, and then plugged in the USB mouse, no hang. Pointer(s) and click functions correctly.

For me, this is a work-around - I can work around it. I am not worrying about it more.

but I don’t mind if you can explain it. Solve it.