User Profile Service won't start

I can log into all of them. It's just that once I get into them they have all the same problems of not opening anything, with the addition that I can't get into the command prompt, regedit, or anything else that I would have to use the windows search for.

Would trying to rerun the repair be an option before the clean install?

I'm still working on the backups, and I've been restarting into regular windows in-between to try your suggestions. If that's where we're at at this point, I'll keep going with this and try to run the repair. Thanks for all the help so far, and I'll let you know my progress.

Alright. It took a long time to save everything since I was working with just a 1Gb drive to transfer everything, but that's done now. I attempted the repair and ran into an error code of 0xC0000005. A memory test and chkdsk both ran clean. I read that a few people have gotten this error after certain Windows Updates, and since that was my original problem, I'm thinking that's a likely cause.

I'm thinking of going on and trying to run the clean install and see if I get any errors in that, but I'd like your input first.

I do not, but shouldn't chkdsk have found something if it was a hard drive problem?