Battery indicator not working correctly

Hi,

I've recently purchased a Dell Inspirion 5000. After a few days I realised that something was wrong with the battery. When the battery reached 35%, Windows gave me a notification that my battery was low, when I went over the indicator it said '35%', when I went over it again it said '7%' (only a second or two later). After this the indicator kept saying my battery percentage was at 7%.

How can I solve this problem on a NEWLY bought Dell Inspirion?

Thanks in advance.