HP VP6311 Colour Problem

Question

Hi, I have a DLP projector, model HP VP6311. When I switch it on the colours look great but after 3 to 5 minutes it seems as if one colour (the blue) is lost. What can the problem be? I know that I switched off the projector once or twice without letting the fans to cool it down. This might have caused the problem. Any ideas what has gobe wrong please?Thanks in [e-mail]