I'm getting an error involving a missing .dll file
Firstly, this only works on OS Windows 7 and higher.
Make sure you're running the patched exe. Assuming you are and still get the error, delete your current folder and re-download. If that doesn't fix it, wait until another patch comes out where it does.
It says that no items were received from the Pokestop but keeps spinning it.
You are soft banned. Wait until it's done and you'll be un-soft banned (45-50 spins).
It says idle in the bottom left.
Nothing is near you. Go to a more populated location (Central Park, New York; Tokyo).
Session expired: relogging won't stop repeating.
Just restart the application. This happens every so often for no known reason.
Could not connect to server.
Restart the application and check your credentials.
The auth key isn't correct.
In the off chance that you somehow changed it, it's located in the settings and should be cookies.
Lastly, this is the very first running bot following Niantic's API change. Not everything is going to run smoothly. I'd recommend that you guys attempt these common fixes first and if all else fails, then ask.