Sorry for the delay. I only have a few hours after work each day to play with this stuff.
I tried everything posted and nothing worked. I was frustrated and disappointed. Then, suddenly, I had a vague flash of memory of downloading some film simulation files off a forum a few months ago. Those were the files I’d been using.
I found it online, and they’d since been updated from v1 to v3. I downloaded the new files and they work perfectly. My computer is fine, my RT settings were fine, the pictures look beautiful.
Thanks everyone for the help.