Hitachi 51F500

I purchased a Hitachi 51F500 3 years a go.  I think I may have 2 separate problems.

Problem #1:  Yesterday while watching TV I began to hear these loud noises (sounds like tapping a microphone turned all the way up).  This happened intermittently.  Then after a hour or so, the TV began to shut off and then come back on.  This happened a couple of times so I tried to shut it off.  It would not shut off so I unplugged it for the night.  When I turned it back on today - the same thing is happening.  I also noticed that before it shut itself off today . . . the word "stop" appeared on the screen.

Problem #2:  Today when I turned the TV on I also noticed that there was some real faint blue lines (spriral) in the bottom left and bottom right hand corners.  They are more heavy on the bottom left.  I hit the "magic focus" button and it seemed to take longer to go throuhg the blue.  When it finished the word "blue" flashed on the screen.  This did not fix the problem.

I bought the TV for $1500 3 years a go.  I think you can buy them for $800 - $1000 now.  The reapair guy will charge me $100 trip charge plus parts and labor.  Not sure what the problem is or if its worth fixing.   Please help!!!