Winxp reinstall

[TeresaPuckett1]

I did not have original windows xp professional cd, however had windows xp home disk from discontinued machine, tried to windows xp home disk - got to point where asks for product key which I don't have - cant' get past this. So, I called the mfg Dell and they sent the correct windows xp professional cd. I tried to load the correct cd, but computer will not let me (tried pressing f12 & booting from cd

 

[PhilFrisbie]

Now that you have the correct CD, please explain exactly what you mean by "computer will not let me". What error? At what point in the install?