Cable TV sound and color problem. Please Help!

Hi, yesterday I bought a 47 inch Olevia to play PS3 on. The PS3 works great with HDMI. A problem has recently come to light that I cannot find anything about online. Here is the scenario. I turned on my tv to watch some television and the color was very blotchy and blurry, and there was no sound, just white noise. It was almost as if all I had to do was change the input or something. Funny thing is, it fixes itself after about 10 minutes of just sitting there. I know there is nothing wrong with the TV cause when I play the ps3 while hooked through HDMI, it works absolutely fine with no problems. It's just that when I switch to cable tv, there is no sound and the color is screwed. This is my first LCD screen, so I am pretty noobish when it comes to the settings and such. Can anyone help me out? Thank you very much.

no box, just direct cable hooked into TV. The problem only lasts for about 5-10 minutes after turning on the tv. The ps3 looks fine on the spot, it's just a tv issue.