Down loaded bio update screen is black and laptop keeps coming on then shutting down and coming back on

Shut the computer off and then power it up again. As it is starting press the shift button and F10 and hold. You should get a warning that you are about to reset your computer select yes.

Keep in mind that once it does the reset all previous windows updates will be lost and need to be down loaded and installed through windows update again. Windows XP is no longer supported so not sure if all XP updates are still available.

First - re-seat the hard disk and reboot the computer. If the computer does not boot up then reboot and go into the BIOS configuration to see if the BIOS detects the hard drive. If it doesn't detect the hard drive then it could be faulty.
Then the hard drive needs to be replaced in the computer/laptop, Windows installed and the computer or laptop's device drivers plus your programs etc. to get a functioning computer/laptop again.

go to laptop technicians and make them flash ur laptop bios

Check on Toshiba.com for updated BIOS and firmware. I think it may require updates.

CPU overheat with BIOS version 1.19
Try new ver. 1.25 published on 1/11//2010.

Press and hold the power key. It should shut down (or just pull the power).
Restart the PC and do not press the escape key

It sounds like two possible things. One thing may be that your screen is not working anymore. Can you get a monitor and plug it into your port located on the side of your laptop? If your screen pops up on the monitor this tells us your screen is either in need of replacement or a connection may be loose.

If that is not the case......

Another thing is your hard drive may not be initiating. If you feel confident enough I would open the back where the hard drive is located and make sure the hard drive is not loose. Does it give you any beeping sounds when you turn it on? Can you count the number of beeps? This will tell you what the problem is on boot up. Also, is it a black screen with a cursor blinking?

Maybe you could try the last known good configuration. When the laptop is starting up, wait until the acer screen disappears and then tap F8 on the keyboard before the windows screen comes up. You should get a black screen with some options that say safe mode. The fourth or so option on the list will be "Last Known Good Configuration". The computer should try and load windows. Hopefully that will restore the machine before the update. 

If it works it would be a good idea to go to http://windowsupdate.microsoft.com/ and fully update your laptop. This will download the update manually instead of doing it with automatic updates. 

1. Start laptop
2. When the laptops Logo page closes, start to press F8
3. You should get a Windows Start screen
4. If you get a Windows Logo page (the kind you normally get when Windows loads, then reset it and start again.
5. On the Windows Start page select "Last known good configuration" and press enter twice

Hope that solves it for you =)

don't try to turn it off then back on straight away (with the power button).. this will confuse the computer and keep it on with no back light.

try letting it power down fully before you turn it back on.

ps. if you did not turn it off in the first place then find a update for the back light driver/firmware. also known as bios update :S