Region wont change

[phrasathane]

I have WMP10 and when i installed my old dvd drive and tried to play a
movie it asked said this.

your system is set for dvd region 1. to play this dvd, set your system
to region 1.

i click ok and it takes me to dvd properties. when i try to change to
united states region 1. it says this.

unable to update region setting. please make sure drive contains
region 1 media and you have administration priviledges.

i did this under the admin account with several different region 1
dvds. can someone please help me.