BB Curve :: Phone Is Wiped After 'incorrectly' Putting In Password?

Back in July I brought my girlfriend her first Blackberry, a Curve 8520. With this set-up she has a password lock for the screen, which works fine and she knows exactly what she's doing with. Then about four weeks down the line she tells me she woke up one morning, typed in her password but was told it was wrong and she had 9 attempts left. After looking more closely at it, it was actually asking for a device password - which neither my girlfriend nor me has ever set up on the Blackberry.After doing some research the first time, we tried everything - connecting it to device manager, inputting letters instead of numbers, etc. but eventually had to wipe the phone.So then after setting the phone up for a second time straight after, this morning she tells me the same thing has happened again and she's had to wipe her phone.