grub

Ledya

hi,

So i created usb live with pendrive linux of ubuntu 16.04 and installed it on another USB, so im not limited to 4gb. Anyway on start sometimes i get the black screen with text GNU grub version... then minimal-bash like editing is supported. For the first word. TAB lists possible commands completions. ANywhere else TAB lists possible device or file completions

grub>

I type exit and it takes me to grub to pick OS. I'm using asus vivo stick.

My question is why do i sometimes get that and not all the time. And when the usb with ubuntu on it, is not even connected it takes me to this black screen mentioned above before going to windows. Is grub not only installed on ubuntu USB?

sorry kinda noobish, really curious though