computer:HP Pavilion g6 Notebook PC
cpu fan starts,led blinks but the system fails and turned off with a beep sound suddently.I perfomed hardtest,after that system works well in AC power but when battery is connected the same problem appears.this problem appers occasionally.sometimes the system starts normally with battery and works well.so the starting is inconsistent.i have done memory test,battery test,hard disk test,startup test,tune up etc; all the above test are passsed.please help