Had problems with mine awhile back. Fortunately it was done under warranty but it took an age because - get this - Toshiba stopped making it a while beforehand, didn't make anything else like it and didn't have a stock of main boards, so they decided to get a batch specially made and tested!
It MAY be that your power supply has failed electrolytic capacitors (See this page - http://www.markdigital.com/2011/02/14/bad-capacitors-lcd-monitor-repaired/ )
If that is the case, it may be worth a punt and changing anything that looks suspicious, on the principle that there's nothing to loose.
Failing that, replace.
Because of the debacle with mine and the fact that Toshiba are so in tune with their customers (not) that they decided no-one wants a PVR, I ain't buying Tosh kit for a long time.
Sorry its not good news, but you aint alone