Safari cannot load any Google Sign in pages

Question

I'm on a late 2011 Macbook Pro 13" running 10.10.2 with Safari 8.0.3. My internet connection is fine, and I have no problems in any browser but Safari.
Safari will load any webpage fine, until I try to access a Google page that requires logging in. This includes accounts.google.com, mail.google.com, calendar.google.com, etc. Google search loads fine.
I've tried clearing cookies/cache, completely resetting Safari, resetting my keychain, and double-checked my DNS settings. Nothing has made the progress bar move. I've of course restarted countless times as well.
The problem arose when I tried to install the desktop version of Google Drive. Once installed, it displays a blank window as the sign-in page, and won't let me do anything but close it. I found a ton of similar issues on Windows and IE causing Drive's problems there, so I'm thinking this is a Safari issue at heart (or maybe Keychain, since it all routes through there apparently too).
Does anyone have any other suggestions?

Answer 1

Please read this whole message before doing anything.
This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.
The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.
Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem. You must hold down the shift key twice: once when you turn on the computer, and again when you log in.
Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Ask for further instructions.
Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.
The login screen appears even if you usually login automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
Test while in safe mode. Same problem?
After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of the test.