strange!!!! - account lockout check box greyed out

[RetrogradePAK]

for some reason, my domain users accounts have locked out and when i go in the user manager for domains and open up a user account, the "Account Lockout" check box is disabled (greyed out).

how can i fix this!!!!

 

[RetrogradePAK]

i would like to add that despite my removing the lockout policy, users are being locked out and the account lockout check box even for the locked out users is greyed out!