As I'm sure most of us are aware, there is a problem on the forums of the occasional thread vanishing when you try to post in it and Admin are working to sort it out.
I had it happen to me the other day and I found a way of saving, at least, the last page of the thread if it's longer than one page.
If you click the Submit button and you're presented with a screen that says The topic or post you requested does not exist then use the following to save as much of the thread as you can:
1. Hit the BACK button on your browser to take you back to the submit screen.
2. Scroll down until you get to the previous posts in the thread.
3. Select all the previous posts.
4. Create a new thread with a similar title to last one (I just added "PT2")
5. Paste the posts from your clipboard into the new thread and submit.
Worked OK with the post I had vanish on me and people just carried on posting in it as normal. :D
As Tim has said in another thread "all the missing posts still exist... so we can get them back. We just need to fix the fault before we can get them back to stay" so this is only an interim solution but at least we can still keep the threads going. :mrgreen: