computer wont boot up

I turn on my dell laptop it starts loading and says system bios shadowed

then it says sis900pxe boot romv1.09 hook int18
client mac addr:00of1f bb 36 0d guid:44454c4c-4a00-1056-804c-b9c04f4c3431

pxe-e51 no dhcp or proxydhcp offers were recieved

it keeps looping over and over

Demonbael.. what that usually means is there is no recognized bootable media found- that is to say the harddrive doesn't have a useable bootloader, the CD drive and floppy drive neither have a workable OS on them either. Usually the final boot option is over the network (not as used any more as it used to be- but can be very handy.) Hence it goes looking for DHCP...

When it does a POST, do you see it detect your drives?

If you use a bootable CD, what happens? Can you see the HD from there?

Just a few starting suggestions- please let us know what you find.

i try to load windows again and after all the files are acessed it says no hdd is detected.
it then shuts down installation process

Replace the hard drive...