xps battery problem

Hi...
I have got an XPS 1330.....I just had an unusual problem 3 days ago.....When I turned on the laptop...I got a black screen and a message that...the laptop does not recognise the charger and therefore it will not change the battery....The message states the the laptop will try to continue working with this charger but will not charger the battery....It says that it does not recognise the ac power supply and I should use the 65w dell charger....(i m using the same charger and i have been using it since i bought the laptop...along with the charger) when i press f1 as mentioned in the message...my laptop starts normally and is working ok but it does not charger my battery.....as a results i cannot work without the charger....Can any body help..
thanx in advance.. :)