Inspiron 17 randomly stops recognizing A/C adapter

Occasionally, my laptop will think that I have unplugged it. I'll be on my laptop, working like normal and suddenly the screen will flash, and then dim and the battery icon in the system tray will change from a battery with a plug, to just a battery. The A/C adapter's green led light remains on. After a “while”, the screen will flash again, then brighten and the battery icon changes back from just a battery to a battery with a plug.

It is as if I have unplugged the power supply, but I actually have not even touched the cord.

This event has happened 8-10 times in the past 3 months. The amount of time it takes the laptop to recognize that the A/C adapter is still present varies from about one minute to 3-4 hours.

I have checked the connection of the adapter to the laptop, and the connection of the adapter to the wall socket. The wall socket is functioning – tested with a lamp. The adapter is the one I received with my laptop about 9 months ago. I don’t have any other adapter to try.

I typically use my laptop while it is sitting on a table, plugged in. I don’t move it around very much. But, this did happen one time when I was in a different room, with a different wall socket.

I have an Inspiron 17 Notebook (3721) with Windows 7 Home Premium 64 bit

Since I am nearing my one year mark, I am getting more concerned about warranty. Any ideas on what is going wrong?

Thanks for the help.