Question says it all, I'm very confused and this doesn't make sense to me.
I power on my computer, put in my password, and it works just fine.
I leave my computer, the screens turn off after a while. I come back, put in my password, it works fine.
I leave my computer for a long time, the computer goes to sleep. I come back, put in my password, computer freezes for a bit then returns "Invalid password"
I hard reset my computer, it boots, I put in my password, it works fine.
I've never encountered something like this before. I'm running OSX Sierra on a Mac Pro. I don't have too many weird things installed, though I do web development, so I have some utilities installed via homebrew, nothing that's a service.
Any ideas what's causing this? I'm stumped. It started happening about 2 weeks ago, but I don't remember installing any updates or anything else that might have triggered it.