I really can't be very specific on this since I'm not really aware of your complete setup or what 'encrypted' discs are that you may be receiving. If you are using the DVI-D connection at the projector and you are sending the video over 15m then you should be using a HD-Base-T extension system from a top shelf company. Extron, Purelink, and others make very good quality units which properly send the HDCP copyright protection across a single cat-x type cable. If there is some higher interference possible, then use a CAT-6 cable, preferably shielded if you can do so.

For testing, I strongly recommend that you temporarily place the player close to the projector and see if the issue is due to the distance you are covering, or if it is due to the player/projector combination. The WD-2000 is a 2006 model projector. That's a 7+ year old design at a time when we are flying through new copyright standards with HDCP and the newest HDCP standards which could be on a new player may show incompatibility with an older projector like that. I wouldn't want that to be the case, but it is certainly possible.

Finally, make sure to try some new HDMI/DVI cables of good quality. Cheap cables are fine when you aren't in commercial situations, but when you are in a top tier installation, it is vital that you go with high quality cables from a reputable manufacturer for long term use and reliability.