Connecting Dell Inspiron 1525 to HDTV

I recently purchased a Samsung HDTV and tried connecting it to my Dell Inspiron 1525 which I had bought three years ago. I used a HDMI cord and it worked fine the first time I plugged it in but now I'm having trouble getting a signal. Now when I connect the two the tv shows "No Signal" and when they are not connected, of course, it says "Check signal cable". I also have a PS3 and that works perfect with the HDMI cable.