Just wanted to give a solution for an issue that I had on a Dell Optiplex GX270, where it was having problems hanging when a couple of peripheral USB items were plugged in. After I had installed an HP printer, I plugged in an 8Gb thumb drive. It would hang for a very long time until I finally had to reboot. When it went through the short Dell setup screen, it just went black with a flashing underline in the top left corner instead of going to the first Windows startup screen. The funny thing is that I would unplug the HP printer's USB cable while the computer was still powered, and it would immediately start Windows. Through several different test cycles I found that A) Leaving the printer USB cable plugged in during a restart brought up the blank screen w/flashing underscore... B) Not connecting the printer USB cable during a restart brought Windows up properly... That told me that there was a problem with BIOS. I went to the Dell website and flashed my BIOS with the latest update for my computer. That resolved the issue immediately.
Hope this helps others resolve similar problems, because it seemed like there