I think this is a good day to remind NaNo novel writers to back up their files if they haven't already done so.
Typically, I'm very punctual about backing up my computer. I'm paranoid about losing files, and schedule a backup at least once a week, more if I've put in a lot of work that week.
But as life gets busy, my fingers are busy typing my NaNo novel, and my mind dreaming up new conflicts for my MC, my computer backups have dwindled to almost zero.
I own an external hard drive for the sole purpose of backing up my files. Over the years, I have lost too many files to risk losing them again. And when you lose a novel...it's like you've lost a part of your body, your soul. A part that there's no getting back again. Ever.
I've been writing this novel for 19 days now. This is a novel I couldn't replicate if I tried. When you put a lot out on the page in a short amount of time, it all blurs together, and it's hard to remember the majority of it. Even if I could remember it verbatim, I've been typing this for 19 days. I'd like to not have to use another 19 days to re-accomplish what I've already done.
So don't learn the hard way. Get an external hard drive and back up your computer. It's well worth the investment (and they're affordable). And once you get the external hard drive, use it.