External Hard Drive didn't recognized

I have Seagate Pushbutton Backup 300GB External Hard Drive using it since several months ago and worked perfectly until yesterday. I had to disconnect and reconnect it in order to connect to the good. I get a message saying that it is not being recognized.

I tried it on another computer, it works perfectly well. I am using Windows XP Service Pack 2 and the hard drive is plug & play.

So what exactly is wrong over here?

Check USB Flash memories. I suppose it is the only thing because of what the memory stopped working or also Windows has trouble loading the driver Plug n Play.

Could be enery problems. Some USB devices may commonly exceed energy consumption and give messages just like yours.