DLP no image at time - no chime - lamp light blink but no image - sometime 3 front panel lights blink

I have a Samsung HL-R5678W DLP TV.
Recently the TV developed a problem.

While changing source, the TV screen will go blank although you can see the lamp on at the back.
Sometime the problem is seen from the get go, no image, the lamp is on at the back, the TV won't turn off, the front panel lights will be off, no sound, no display on the screen.
You power off and then the green lamp light indicator at the front will blink and goes off but after couple of seconds no images on screen and no channel changing, the power off won't turn the TV off, changing the source does not seem to work (no sound on any channel although there is some being broadcasted on some channel).
I have seems by 2 times the 3 front panel light blinking indicating a bulb replacement but then this error does not reproduce all the time.
Yesterday, my wife and kids watched TV all day (I told them not to turn off the TV and not to change chanel), I turned it off at night when going to bed and this morning no image again although lamp light at the back is on.
This morning I noticed that the lamp light never turn off yesterday when I powered off the TV, I unplug the TV power and power back the TV, green lamp indicator light comes up on front then goes off but no image still and no power off from remote or front panel button,

This is driving me nuts, please help, would like to know what could be wrong and how much it might cost before bringing in a tech,

Thanks
Laurent