your mobo/BIOS into thinking it had a bad shutdown. Thus it defaulted to a safe memory speed setting, thus a slower CPU clock.
Probably defaulted to 100MHz. Simply go into BIOS and set it back to 133 MHz.
OK, I know this sounds wierd, but it has really happened and I'm bummed.
I have an AMD Athlon XP 2200+ (1.8 GHz). Everything was going smoothly until--as usual-- I had to format my HD and reinstall XP Prp SP2. After installation, for some reason my CPU is recognized as AMD Athlon Xp 1500+ (1.3 GHz). It is really killing me.
I would really appreciate it if someone could tell what in the world is wrong!