I've heard of the press method. I didn't mention it because that's a temp fix. I've heard of it working, but usually only for a while. It's not something you can do and have it work "forever".
My friend had a plasma TV that had the red dots on the top left corner of the screen. There was nothing to be done but suffer with it. He bought a new TV finally last year and the whole thing works again. You can check the cable or cable box, but odds are it's the TV.
This is a plasma or LCD right? Try flicking your finger nail against the screen where the dot/s are. NOTE: you're NOT hitting it with your hand, just with one finger. You can do it hard enough that it'll hurt your finger before you hurt the screen. Sometimes they'll go away, if not then your only option as previously mentioned is to replace it.
If your Mitsu is a rear projection TV it probably has a DLP panel. It consists of millions of tiny mirrors on flaps that are moved. Each mirror is one pixel and when one breaks you get a white or black dot. The DLP panel may be replaceable. You can check with
Or maybe it's time for a new TV?