Yes i do have another computer, i tested the usb stick and it does boot from it, no problem.
And Yes i can boot into Windows without that usb attached
No, i dont have an external hard drive but i dont Think that the ports are the problem, this problem occurs with any of the ports that i use..
Question : does the bios have like a maximum usb boot drive size? I mean, IT will allow booting from a usb that is like 8gb maximum?