Copying to Word was my backup until I switched to Google Chrome. It was shortly after switching from Explorer that I realized how unstable it is compared to Chrome. Since then I haven't seen a similar problem except once when a post I was proofing posted while I was making changes. That could have been operator error since I had entered the captcha numbers in prior to proofing.<quoted text>
Google Chrome lets me backspace and my words are still there. Sometimes, if it's a large or important post, I'll also copy the entire thing, just to make sure.
Anyway it has been much better since switching. Plus it doesn't lock up like IE did.