Hi Blessed Almond,
I'm sorry you've had this happen - very frustrating. I'm also not sure why this happened as I'm not aware of any such time-outs on the forum software. I've certainly never seen it or heard of it before - has any other member had this happen?
In terms of recovery, your browser's Back button should be able to come to the rescue should this happen again. If "Submit" fails for any reason you should be able to click the Back button (more than once might be needed) to get back to the relevant Edit page.
BTW, to pick up your point made in your other post about searching, the phpBB forum software is what it is but if you want to do a power search then you can always go to Google and enter a search string in the format
your search terms site:cameralabs.com/forum
For example, check out this Google search