Yes !! I activated XP on a system I built with a genuine XP Home OEM Disk and did all updates on my own B.B. I registered it in my cousins name (for whom I built it).
When |I set it up at his place I got warning that hardware had significantly changed and I needed to revalidate even though no hardware had been changed.
I phoned Microsoft and after 3 1/2 hrs on the phone with support in India trying to change things in the registry they finally gave up and gave me a new product key which is what I suggested they do in first place.After a reasonable time , I insisted thery call back at their expense which fair do's they did.
From my converation with their support people this is not that uncommon an occurence with XP.
I suggest you do what I did but make sure they call you as it is their problem and they should pay.