This isn't an answer, but a comment that you're not alone!
Same thing happens to mine. It's about 20 months old, and it's intermittent. Often, switching off on the front, waiting a minute, and switching back on will make it start up. Seems to be more reliable when the room is warm and dry.
When it doesn't start up, the fluorescent tubes don't illuminate, so at a wild guess there could be some problem with the starter, or something else stopping it even reaching that part of the startup.
If it gets worse, not sure how to get it fixed cost-effectively. It's out of guarantee and didn't take the extended service option.
Great TV though.
TX-37LZD70 owner, December 2009
