Hi --- I have a Panasonic 36" TV with a problem-

There are rings - just like a bulls-eye - of color that appeared on my TV today. A green solid circle in the middle of the screen with various shades of violet in concentric rings moving out to the edge of the screen - it is really bright and they appeared suddenly...

Do I need to buy a new TV or is there a simple fix?

PK
San Diego, CA

This may have been caused by a magnet or magnetic field. There are degaussers (they remove the manget charge) that can clear this up.
Here's one such source:
DC-13 Color TV and Monitor Degausser

However, a local TV repair shop will likely have one and can either fix it for you or may rent the degaussers to you.

I agree with Northwind, it sounds like a degaussing issue - and I'd suggest that you have it 'fixed' by a TV shop (or really read some info about the procedure - you can make it worse). Be aware that stereo speakers sitting next to the TV will cause magnetic interference if they are not shielded. Virtually all computer speakers and home-theater speakers have this shielding, but not ordinary stereo system ones.