Xbox360 not working on my Tv?

Heya, had a problem where I was playing Guitar Hero, then finished, turnt off my xbox360 for awhile, went to play it that night, and it DID turn on, but my tv screen was all blue.

I didn't get the rings, my Xbox360 seems to be working fine, except for the fact it won't come up on my tv, I tried all channels and av channels etc but still no luck.

I thought it would be the cable going from my xbox into my tv, so I bought a new one (VGA Cable - I believe). tried that, and still no luck.

So, if anyone knows of any solutions, or if this problem has happend on your tv, please let me know.

Thanks

(I don't think it is my tv though, as other consoles work fine on it)

What I meant was what exactly happened before you turned off the system?

Also I was saying that if might be the connectors, as in the ones in the 360 not the cables. As someone else has stated it could be the GPU I guess. I don't know a lot about that stuff though.