Although there are other possible causes for the symptoms, there is a possibility it could be a faulty cathode ray tube. At the very least seems somethings up with the drive to the tube.
I would get back to your dealer ASAP because if it's out of warranty by only a few weeks they probably can help you. If they can't, contact Philips Customer Service in writing, if it's tube failure they almost certainly would be sympathetic to you, if it has failed within such a short time. You may also have certain consumer rights, irrespective of the warranty offered.
Cobweb
January 2005