Also asked at
https://duc.avid.com/showthread.php?t=390940 Please follow the DUC rules and do post multiple times for one problem. Doing so wastes other users time here responding to you and not being able to follow all the separate discussions.
You need to provide lots more details. Start at "help us help you" up the top of each DUC web page. See the info expected there, and standard troubleshooting steps.
Most clicks/pops are caused by trying to operate with too small an IO Buffer and "ignore errors" enabled in Setup>Playback Engine. Leave ignore errors unchecked. Set the IO buffer as large as you can and uncheck ignore errors. Does it stop the crackling. Now try to set the IO Buffer as small as you can to reduce latency. All native DAWS are always a trade off between latency and stability. Make sure to properly optimize your system to make it run well.
The other source of problems like this is improper digital clocking, e.g. if you are recording via S/PDIF, AES/EBU, ADAT etc. You need to tell us exactly what interface you are using, any outboard gear etc.
Very rarely driver problems or other things can cause this, make sure you are running a driver compatible with your OS version, and ditto for Pro Tools.
Is Guitar Rig 6 claimed to be compatible with the version of Pro Tools and the OS version you are running it on. You need to check all that.
If you are still stuck and need more help here, post a SiSoft Sandra report. As well as describe your interface, driver version, what you have done/tried etc.