Hdmi/dvi & cable tv

I bought an Insignia HDTV LCD a few weeks ago. I connected the cable box via its DVI output to the HDMI input for video and I use an optical digital audio cable for sound and it worked great. All of a sudden though, I am not getting any video or audio (the screen first started flickering, now it's black). I checked the cable box so I connected it with component cables (only checked video) and it worked. I read up on similar issues and it sounds to me like a "HDCP handshake issue" - but how do I fix it? The HDMI cable I bought was cheap, could that be the problem? (I read up on that too - seems like the high-priced ones are not better really). Are these HDMI cables delicate? Could it simply be defect? I realize I could simply connect via component cables, but it bothers me that I got it to work just fine and now would have to do that. thanks in advance for your recos!