Internet error

Hi Guys

Please Help me, i don't know really what happen to my mobile phone. i am using nokia 6120 classic , i can access to internet at anytime but when my mobile shows the battery low i just put my charger to mobile ,,after my internet also cut automatically and i can't do anything with pc suite or anything ..when i remove my charger i can access internet, PC suite .what i do ??? i never heard and see this type of complant ...what is this all??? Buddy's please need help ,,,its happening to any guys??? ........