If you are unable to launch Photoshop Elements 12, 13 inspite of signing in with valid credentials, try one of the solutions outlined in this article.
If selected, clear the Use a proxy server for your LAN option for your browser.
For Internet Explorer:
Look for software on your computer that could hamper network communication, and uninstall it.
For example, uninstalling BrowserSafeGuard software fixes the issue, for some users.