How does a license for XP that came from the manufacture with the computer change to an unauthorized version after two years of use as an authorized license? Should I contact the manufacturer or Microsoft?

Your post is the third in the last couple of days. Microsoft is continuously updating their verification process. I haven't looked but suspect they released something that has caused the flagging of some systems. I would try Microsoft first.

Hmmm, All this is third hand so take its worth as a grain of salt. People buy xp only to find out that their key is invalid. Pirates using a key generator already activated their copy and the key just happens to be the one that comes with the new cd. Bummer! Programs can get your IP..location...and OS. With a few key stokes your keys...Just to many keyfinders on the internet. Bummer! SIW if installed can give a hacker all your information in the secretes section. Bummer! Microsoft is updating and looking for duplicate keys and illegal keys. When they find one ...everyone using that key gets invalidated.....What choice do they have? Each new piece of hardware adds a point to having to reactivate, and having automatic updates and WGA running lets Microsoft know if you are over the limit. As a re builder on a unsecured network I have had 2 MAR systems come back as the keys were hacked and the computers were deemed invalid. These were MARs OMG! The Internet is just ...hmmm ...Amazing. Call Microsoft.

worldlibrary I agree with your post above. However, the OP indicated that WinXP came with the computer. I am assuming that means HP. I am guessing if what the OP as said is accurate that this is a false positive.

The computer was bought on ebay and came in what appeared to be original packaging from HP. What if I had bought a stand alone copy from Microsoft? What would stop hackers from generating and using the license key provided by Microsoft? There are only so many combinations of letters and numbers possible.