Hi jcgriff2,
I have fixed the problem - albeit temporarily, I believe. I didn't want to go ahead and delete the *.sys files - I was trying to find a way to uninstall instead, since they weren't coming up in the windows uninstaller. In searching for a way to do that, I did find a fix for my problem though - by changing the value of Start in the registry editor for riftenabler, from 1 (auto start) to 3 (disabled / only on request), I was able to boot up without any BSOD for the first time in 2 days. I found the solution here, at the bottom of the page.
Thanks for all of your help! I really appreciate it!