Windows xp has dissapeared

[antoine mac amh]

Hello,Windows XP service pack 3 came installed on my pc when i bought it. now I seemed to have gone back to Windows 2000 What has caused this or can i put it right.

 

[hang-the-9]

Well, what did you do recently to the computer? This does not happen if you just turn on the PC on it's own.

If you had XP installed and not 2000, there is about a 0% chance or less that Windows 2000 decided that your computer would be a nice place to visit and installed itself while you were sleeping.