Hang on (re)boot

[bzfbd]

Hi,
I sometimes encounter a hang on (re)boot with 1.39 in that at the Press F1 ... Enter screen I get one '.' at the end and it never continues. I left it sit even for 24 hours and nothing anymore. Any way to debug what's going on?

[bzfbd]

Seems it's USB enumeration. With some physical access I removed the external active USB HUB and the boot continued. I also tried to pin-point it to any specific device attached but couldn't. Now to figure out how much of that can be disabled .. or fixed. Help still appreciated.