Intermittent errors are always a pain to identify. A few more details MIGHT be helpful:
- You were able to create a new thread, have you gotten the error when creating a new thread before?
- You were able to respond to a thread that you created, have you gotten the error when responding to a thread you created before?
- When in the process does the error appear? When you click "reply", "Quick Reply", when entering text, when you hit submit?
- What OS, Browser, and versions are you using? Is everything fully updated?
I know, it's a pain. I've worked in IT, web services, and support services. I get it.
Then there's always the, "Have you tried turning it off and back on again?"