Sounds like a case of RF interference creeping in somewhere...
Could be from the cable running to the projector or actual RF interference messing with the WiFi on the CCast or it's connection.
You will need to determine where the static is coming in first which means
1 - try replacing the Projector with a TV and see if the interference is still there...(This might be difficult if the projector is ceiling mounted and the cable doesn't have a lot of slack, in which case jump to step 2)
2 - If yes try replacing the cable (from AVR using the TV again) to see if it goes away. If it does you will need to replace the cable to the projector. If no affect then you can plug the Projector back in using the original cable since you now know that isn't the problem.
3 - If that doesn't work and the static remains then try and move any nearby cables away from the CCast to see if that helps. If you do this while actively streaming something, moving the cables should have an effect on the static you see on the screen. If it does but you can't seem to find a happy place to make the static go away, then think about replacing some of the cables you use with new ones that have better RF shielding (Replace with COAX).
4 - Next thing to test is the CCast itself and eliminate the AVR. Try plugging the CCast directly into the test monitor and see if the static is there. If so then you have a faulty CCast. If not try again plugging the CCast directly to the Projector and see if there is static there. (This also helps eliminate the projector if you can't try Step #1) If not then the likely cause of the static is coming from the AVR.
5 - If you find it is the AVR, I suggest trying a different input on the AVR (at least temporarily) to see if the static returns (this will eliminate the input as the problem) If no static then it's the original input which may be dirty, Get some compressed air and some spray in Contact cleaner (make sure to power off before you spray) to try cleaning the input and try it again. If the static moves with the input then that static must be coming from the AVR or cables you are using.
6 - Final test if all others fail (Identify the bad cables)...Unplug all the other devices from the AVR (move them away from the AVR as much as possible) except the CCast and see if the Static remains. If it goes away then one by one, plug in each device and check to see which one causes the static to return. If you find one that does then Unplug it and continue and repeat until all the other devices are plugged in without static. At this point the majority of your devices should be plugged back in. Any devices that are not need to have the cables replaced as they are probably leaking RF. Buy Shielded versions of those cables and pray they are good enough to get rid of the problem. If not you might want to think about replacing the devices themselves. If you still have static when there is nothing plugged in but the CCast then your AVR doesn't really like the CCast signal. You can try a different CCast or Worst Case need to have your AVR repaired. Make sure you give the repair guy the CCast to test with.
Most people with an AVR setup find RF noise to be a common problem. Especially if they have a few devices that do not support HDMI and use RCA (Phono) connections which are notorious RF leakers. You should always buy Coaxial RCA for use with AVR's since the close proximity of all those cables is an RF nightmare.