First, do you mean
Panasonic Notebook?
All notebooks/laptops are unique animals; so be very, very careful when upgrading the OS. These systems require very unique drivers and configuration. So doing an install like you would do for a desktop PC is likely not to work.
You fail to state what OS is now installed on your Panasonic and exactly what XP you are trying to install (WinXP Home/Pro SP?). This is critical info you should provide to get help.
Having said that, upgrades to the OS should be done by first booting to your existing desktop, then inserting the Setup CD, and use the Upgrade Install option.
WARNING: If you are actually talking about
Vista to WinXP, I don't know if this will work.
But you will likely have to find a way to do the install from the desktop so your notebook's unique drivers and configuration get ported to the new OS; but
Vista drivers MAY not equal WinXP drivers.
You may have to contact
Pansonic Tech Support and see what they say about your WinXP install, especially Vista to WinXP. You MAY have to get a Panasonic WinXP Recovery CD from them to do that.
If you
are talking
Vista to WinXP; my suggestion is. because this is a laptop, DON'T. Stay with Vista.