I had a similar problem with some other make/model. I found a nice local repair person and 600 bucks later the screens were back in service.
I used a phone book and phone to track service down. Toshiba failed to put such service contacts on the web when I was looking.
I inherited 2 JVC plasma screens with my business location-unfortunately behind a security barrier that makes on site service problematic. Question- after several months of non-use, due to replacement of associated dvd player, the screens are now automatically turned off and self diagnostic lights are flashing. Any attempt to manually overide, turn off/on, unplug per manual has been unsuccesful-except for seconds of regular play, then resumption of screen "sleep mode". Any ideas for self-help regarding sequencing of restart procedure?-otiskat