I'll be more specific: my computer is a TOSHIBA Satellite U505, when i turn it on,  there are two options F2: Setup and F12:enter boot menu. If i press F2, i go to "Aptio Setup utility", here i can change the boot order, there are three options:
 
Boot option number one: TOSHIBA MK5055GSX
Boot option number one: HL-DT-ST DVDRAM GU10F
Boot option number one: Realtek boot agent.
 
I have changed the order to all the possible combinations and i still have the same results. 

2010/3/21 Steven P. Ulrick <lists-fedora@afolkey2.net>
> On Sun, Mar 21, 2010 at 4:04 PM, Andres Felipe Acosta Gil
> <pipeacosta@gmail.com> wrote:
> > Hey all, i shut down my computer with a usb memory connectad, then i
> > disconnected it when the computer was turned down, when i turned on the
> > computer, a black screen appears and a prompt (i cant type anithing),
and
> > fedora or windows doesn't boot. What should i do??
>
> Go into your PC's BIOS right when it boots.  That's usually done by
> holding the Delete key during boot, but your PC might use a different
> key.
>
> Your BIOS should have a "Boot" section.  Look over the items in the
> boot order listing, then make any changes to ensure that both the
> listed devices and their boot order is completely correct.
>
> On my own box, my Supermicro X7DWA-N motherboard mangles the boot
> order every time I change the connectivity of any storage devices.
> The result is almost always that I cannot boot until I myself do what
> I just told you to do.
>
> And yes, that is a glaring firmware bug, and really inexcusable for a
> high-end server motherboard, but there it is.

Hello Don,
I almost did not read this thread, since the subject said "Shut down" and
not "Boot Up"...  But I'm glad I did not pass this by!  As soon as I
reboot, I'm going to try this on my SuperMicro 5046AXB.  If I leave my MP3
player plugged in when I re-boot, my system will not start...

So, off to my BIOS...

Steven P. Ulrick



--
Andres Acosta