Make a note of all settings, then delete your LW prefs folder whilst LW is CLOSED; instructions here: Deleting LW Preferences folder in OSX

If still problems, then go to LW's preference settings (keyboard shortcut Command-Comma ⌘ ,) -> Advanced -> Performance ... and disable all options on that window. Then go to File menu -> Disconnect, wait a few mins, then File menu -> Connect.

If it connects, then can enable settings under performance again.