Hi Dean,
You need to create a little diagnostic matrix and start eliminating causes. Here is a suggestion.
1. Is the popping always coming from the same speaker? If YES, then try swapping the speakers with the other side. If the popping moves, you have a problem with the speaker. This is usually an issue with bad solder joints in the crossover, but it sounds like this is under warranty, so just get the speaker replaced.
2. If the popping stays put, check if this is in the wireless channels. If so, follow Raol's suggestion and try running temporary wires to the rear speakers. If the problem goes away, you have a defective wireless setup and should get it replaced (IMHO, this is most likely. I am not impressed with the quality of most of these units, and avoid them.)
3. If it is a wired channel, check the speaker connections. Look for places where the wires are close together, especially for loose bits hanging free. They can arc over at high levels and cause this sort of problem. Swap the speaker cables between the problem channel and another. If the problem moves, you have a wiring problem.
4. If none of this has fixed it, you have a problem either in your amplifier or the source material. Try running analog wires from the BluRay player to the amp. Does the problem go away? If so, try running the HDMI directly to the TV and use the internal speakers. If the problem goes away, you have an amplifier problem. If the problem follows, you have a problem with the Blu Ray player and should have that replaced.
Hope that helps. The general rule is to take it a step at a time, change just one thing and see how the problem changes. Since there are only 6 components (speakers, receiver, BluRay, wireless rear, speaker cables and HDMI cable) you eliminate each as the source before movin g on to the next.