I have a fairly powerful system, QX6700 CPU, 4GB PC2-8500 RAM new motherboard etc etc
I have a Freecom 400GB External USB 2.0 Drive which is pluggedi n constantly for backup, however, if I forget to turn it off before a restart of my pc or booting from cold, the pc will not boot. The option to boot from USB is disabled in the BIOS. The pc will get so far, reset itself and start all over again. Turn off the external drive and everything is back to normal. The external drive has its own power supply.