Inspiron 1440 Not Charging

As stated in the title, I own a Dell Inspiron 1440 with Windows 7. I have had it since Christmas 2010, and it was previously refurbished. A few weeks ago, the end of my laptop charger was bent slightly and the battery stopped charging. Whenever the charger is plugged in, I get the dialog box that says, "The AC power adapter type cannot be determined. Your system will operate slower and the battery will not charge. Please connect a Dell 65W AC adapter for best system operation." Of course, I am using a 65W adapter. Additionally, the BIOS screen says that the adapter is unknown.I can still use the laptop as long as it is plugged in, but having it shut down within three seconds whenever the charger comes loose is a major inconvenience. I have tried removing and replacing the battery (which I just got last Christmas) and uninstalling then reinstalling the Microsoft ACPI-Compliant Control Method Battery in the Device Manager. At that point I ordered a new charger (the exact same model as the previous one), only to be faced with the same problem (though the indicator light has been flashing on the new charger, unlike the old one). Is the battery to blame? Or is there something wrong with the port in the computer? Thanks to anyone who may reply.