"XP. Must Activate Windows Before You Can Log-on"
11 Jan 2012
Summary: must install Internet Explorer 8 & then system will activate automatically for you.
Windows XP Professional.
Had to do a repair operation.
Used Windows Professional with service pack (SP) 2 for repair.
Installed SP 3.
At boot after SP 3 install, "Must activate windows before you can log-on"
Told system to activate but then system hang with blue screen.
Problem was installed Internet Explorer 8 was replaced at repair operations.
Get Internet Explorer 8.exe on your computer.
Reboot into SAFE mode.
Install Internet Explorer 8.
When asked if want to activate Windows now, answer yes and then wait.
Enter Windows key.
If key has been used once, call Microsoft, explain and get new key.