Help Data Access via mobile network automatically checked

Hi All,
I have sony xp x10 and the problem is:
The Enable Data access via mobile network checkbox is checked automatically :mad:.

I tried with Network info by dialling *#*#4636#*#* and disabled the data connection as well,

But still the Data Connection is getting automatically checked, its quite annoying and weird,:thinking: i have not seen this before '

Please help me friends , always its getting connected and i am loosing my prepaid balance.