DLP (Digital Light Processing) TVs use lamps that have a limited lifespan before needing to be replaced. It's the same with projectors (did you know that the chances of a bulb blowing are directly proportionate to the importance of the presentation you're about to give? At least, that's what it feels like...)
With replacement bulbs costing several hundred pounds, you'd hope your bulb lasts at least for its expected lifespan.
Toshiba say that the life expectancy of a bulb in their DLP TVs is between six and eight thousand hours, depending upon the brightness setting. Even under less than optimum (consumer) conditions, a bulb should last between three and five thousand hours. At 4 hours viewing a day, that would mean a bulb should last for around two years.
So, quite a shock for some Toshiba customers whose bulbs were burning out in just a few months.
Now of course we know that bad experiences make the headlines much faster, and are triggered at a much lower threshold, than good experiences, so we can't say that this is an indicative problem with either DLP technology, or with Toshiba's TVs.
Even so, it could get pretty expensive for owners if they have to replace their bulbs up to 4 times a year.