I have a KDF-E50A10 and the it turns off and then back on. Very upsetting as the tv is inly 4 years old.Was told that it could be the lamp, but do not want to spend money if this is not the problem.

I am pretty sure it is the lamp. Particularly if you had not replaced the lamp before. Typically the lamp has a 3000 to 5000 hour of usage. It is a common symptom of the lamp before it out right fails. The part number is XL2400. I know the lamp is expensive. It usually retails for around 250.00. If you look at options on line, you can get a better price. I would suggest though to use a Sony Lamp not a generic replacement.
I hope this helps,
Skyassoc