Hello,
Does the projector flash if you disconnect the VGA cable from the computer? Does the flashing image look like a "disco"? If possible, try a known working lamp from the same model projector and see if that resolves the issue.
Either way, please contact Technical Support via the web form on the knowledge base at www.prometheankb.com, select your region/language, Projectors, Contact Us. In the Existing case field input case number: 323188 and provide the projector serial number. (case# 323188)
Thanks!