win xp changes my dail-up password

i have been using xp for more than a year, and my dail-up works fine. but it just changed my dail-up password 2 days ago. i tried to change it back from the control panel, it didn’t work. i tried to add another dail-up link, but the password changedagain. i don’t know what to do. i am sure my password is right since i have been using it a long time, and i can see the password was changed after i keyed in. any solution?