Nevermind! I fixed it!
The recovery disk I had on my thumb drive just didn't want to put as much effort into it as recovery disk I burned to a CD a while ago (I downloaded the ISO for the recovery CD from NeoSmart while they still hosted them for free, but I downloaded the ISO on my USB from some other website I can't remember). While doing some housecleaning (it's pretty sad to see me do such a thing- I'm either really stressed or really happy whenever I house clean) I found an old Windows 7 x64 recovery CD that I had downloaded from NeoSmart.com before they stopped hosting it in favor of some paid service. I decided to give it a go, and it worked! In the third paragraph of my original post, I said that the Recovery Disk on my thumb drive told me "Failed to Save Startup Options", but with the Recovery Disk I burned to the CD, it told me to reboot my PC and (after waiting about 10 minutes for the System Restore to check and double check itself, and then reboot again) I'm back in Windows 7!