Boot not posible with usb enclosure

[gianry]

I've an hard drive that correctly boot inside the laptop but not in an external usb enclosure
I've set the boot sequence.
it correctly do the boot till the windows 7 logo . after that laptop reboot.
why ?

[dr_st]

Windows does not like running from USB devices. It requires special configuration with Win8/10, and is impossible without hacks on Win7 and earlier.

[gianry]

I've made the boot from usb drive with another one .
I dont think it is impossible

[mpcook]

I have booted from a USB drive with W7 in X220, W520 and T420's with no issues. However, the boot drive was created while installed in the laptop, then moved to an external enclosure. Cannot determine what the issue is with your laptop. What laptop is this?

[gianry]

I have booted from a USB drive with W7 in X220, W520 and T420's with no issues. However, the boot drive was created while installed in the laptop, then moved to an external enclosure. Cannot determine what the issue is with your laptop. What laptop is this?

the laptop is SL500 . I dont understand what has changed , I made the boot from usb many times with this laptop-