I'm sure that the problem is a result of the current load problems with the boards. I've seen several threads that have this problem and I've not seen any of them that were ever fixed, I'm sorry to say. There may be a way but I've not seen it happen. Others here might know of a way to get them "repaired" so that you can post to them again.
In most cases, new threads have been started with a link to the old thread as reference only with a note not to try to post to the old thread. I don't know if there is anything that a moderator could do. Is it possible to make a copy of the thread? Maybe the copy would work and you could then prune the old thread.