Hi, Have a Philipsmagnavox 26 fla...

Hi, Have a Philipsmagnavox 26''-27'' tv made in year 2000. Model #TR2503c221 SN# 50617722 Many months now has been turning itself off on its own, I would turn it back on and it starts fast flashing on screen black on bottom and bright skinny white line in center and can see picture fine on top.It will usually turn off some times within 10 seconds, sometimes minutes and sometimes stays on. However its getting worse and worse, today has been flashing non stop, but stays on. irritating watching half of something!! Would like to fix. can you figure out what the problem is from what it has been doing? Thanks need help!!-Glenn