Why do I have a blue fuzzy ring of light on my screen that is more noticeable the darker the picture is?

If you have a Sony TV, then the optical block has failed. A new Optic block is 300-600 dollars depending. Not user repairable.

Try going into set up menu and look for a screen degauzing function or try setting the screen temp. to warmer or cooler.

friend maybe your LCD was broken or loose. try to pull gently if it return to normal image.

probably dirty or broken print head. suggest you replace it or get new blue cartridge if your machine has seperate colour cartridges.

bad connection but where need tech.

If you wish to get some details; visit the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.

Projection TV's use a cooling fluid around each of the 3 CRT's that the light has to shine through. Over time, it will grow a bacteria in the fluid (just like sunshine on the ocean) and turn cloudy. The blue CRT is most subject to this. You need to have the fluid replaced, which can be a messy job better done by a pro, but many have done it themselves. If you are interested, I'll go into the details.
Might want to replace the convergence amps while your at it.
Hope Ya Fix It!

Is the XD Demo on. This shows half of the screen with the XD picture engine on and the other with it off. Check your picture settings in the menu.
Good Luck

Uh Oh! blue screen of death. Your light engine has warped a little from overheating and is distorting the picture.

My suggestion to you is to get on the phone with hitachi and start complaining, then keep complaining until they agree to pay for it. You may have to get the problem diagnosed by a pro before they agree to pay for it though.

sounds like 2 different problems here. first problem sounds tuner related. second sounds convergence related. third issue (cost effective to repair ?) at this point i would replace the set. i hope this helps