Apologies for the discomfort. I've had the same issue happening to me in the Forum from time to time, but for a while haven't experienced it. I'm not quite sure why my problem went away for me, as it happened identical to @tbelldesignco. I.e. when I quoted text or replied to a discussion it came up with the same error pages. I have a perfect understanding for the frustration.
This problem has been reported to @Un4saken, our Chief Admin a few times. If you search the Forum you will find the reason why this may have been happening:
Our Host is Contabo, and they have ModSecurity enabled that triggers Firewall issues such as what we are experiencing in the Forum. Looks like the only way to solve it is to turn off Modsecurity, and this will not be happening soon. Not while we are still with Contabo. We have many more issues than just this one, so it's on a list of issues in order of priority. Hopefully we may have your understanding in this.
@tbelldesignco Not sure whether this will help, but let's try this. If you could PM me your IP I can feed it into our "allowed IPs" in the WHM and who knows, maybe that will help. I seem to recall it was one of the things I did when I was going through this problem. I did it with @Rave's IP too.