Disconnect the computer from the internet again. Go back to the usable computer and your usb device
Download ComboFix.exe
Try again to boot the infected computer...fingers and toes crossed again.
Hopefully you will be able to run this on the infected computer...
Double click combofix.exe & follow the prompts.
When finished, it shall produce a log for you. Post that log in your next reply

Note:
Do not mouseclick combofix's window while its running. That may cause it to stall