I'm getting the "Fan failed. Lamp will automatically turn off soon." Error message, randomly. Sometimes after an hour, sometimes after two hours, or sometimes just 30 min. The two identical large exhaust fans are both spinning when the error pops up. I've had two of these projectors for three years and in that time I've replaced one of those large fans on each projector with the same message. There are two other fans inside besides these. Is there any way to know which fan/fans this message applies to? Or is the message simply triggered by excessive heat? Could one of those large fans be damaged, but still spinning? I've heard of others getting this error because there was dust blocking the inside of the machine and they recommend blowing it out with compressed air. Anyone have advice on how to work through this problem?