Bios Setup Will Not Load With Hard Drive Attached

Hi all, help please.

Just changed over my motherboard (Asus P4R800-VM) and CPU (P4 2.8ghz) on my brothers PC.

Successfully installed the Mobo and CPU, previously has Vista installed, decided to put XP on the system, so when the PC was loaded up the XP setup loaded and asked to format partition to install XP over the old Vista install.

This was sucessful, installed XP files and then went into the standard reboot to complete installation, which is where the problem is occuring.

Since this has been done the Mobo Posts but then it hangs, it does respond to 'del' being hit if done so early in the Post yet when this is done it will not enter the BIOS setup, it simply hangs.

If I pull out the HDD it will enter the bios though, it's odd.

Does anyone have any ideas I am completly lost!!!!

Thanks in advance everyone!!