I have been through most of the suggestions other people have had answered, but still cant format the hard drive.
Even tried an old MSDos disc but the pc says no disc in drive. Ive tried bootong through xp disc, using original disc it says Ive a newer edition, which is the sp2 disc. Using sp2 disc still wont boot through or as someone else has said , restart thru dos, I dont get the option.

We had a Trojan get in and seems to stop us deleting it, progs its in and sets its own home page, despite numerous changes back again. Only resort left is to format, Its a Maxtor Sata drive, about to try the back up drive 'F' and format 'C' through that. as when I right click the format option wont let us format 'C'.

any other thoughts pleeze

Hi Windy

Let me just say XP does not run on a DOS platform.
sp2 is Service Pack 2 and does not contain any boot files.
What you need to do is go into the BIOS and set the boot sequence to CDROM first.
Save and Exit.
Make sure you have the original XP disk in the drive, it may also be an OEM disk which states "For re-installation of XP on x pc only".
Choose to delete C only and install XP to that.
For a more detailed, graphical explanation of how to do this, download, if you can, the "Walk through of installing XP" in my signature.
Be aware that what you see is only a running program and not the actual installation of XP.
This you will have to do once you have seen the program.

Wolfeymole, thanks.
altered bios and formatted via the auto programme install.

now working ok, was a problem after antivirus ran out.