compaq presario model 7478

i have a compaq presario 7478 when i turn it on the compaq screen comes
up the after 6 secounds it will restarte iv tryed to use the restore cd
that will not work. iv also tryed to get in to bios to solve the
problem but it will not let bios come up either. is there any one that
knows or have had this problem before that knows how to get it to work
or to get windows to start if ican get it in to windows i can fix it
but geting it there is the problem at the moment.

Try to remove all USB devices. I have the same model and have
discovered that booting from the CD doesn't work if you have ANY USB
devices attached.