My freeze on startup issue seemed to be related to the proxy settings. I saw the username\password dialog on startup, but Eclipse froze whenever I tried to click ok, cancel, or even just click away from the dialog. For a time, I was seeing this authentication pop-up with no freeze issue.
To fix it, I started eclipse using a different workspace, which thankfully didn't freeze on me. Then I went to Window --> Preferences --> General --> Network Connections
. I edited my HTTP Proxy entry and unchecked "Requires Authentication"
. Then I started my original problematic workspace, which launched this time without freezing. Success!
I had no further issues when I re-opened my workspace, and was able to re-enable authentication without having a problem. I didn't see the username\password pop-up anymore on start-up, so there's a chance my authentication info was FUBAR at the time.
Using: MyEclipse, Version: 2016 CI 7, Build id: 14.0.0-20160923