It appears to be like this...
- Sign in.
- Use a plugin reloader to reload the plugins.
- If a plugin's Initialize function contains SendMessage() API, which (for example) is used to tell Plus! to display a notification toast, SendMessage() throws an exception back. That's why the Hopper problem (in the post whose link was posted earlier above) occurs, since I use SendMessage() in Initialize() to retrieve Messenger version from Plus!.
Currently I use a stupid Callback Timer to avoid directly calling SendMessage in Initialize() and it seems to work fine...
Well, Dempsey, I don't really suppose it's Hopper only that interferes with SS3.
Plugin Reloader :: The next generation by Optimism_ has this problem too (at least on my computer) as it shows "Loading plugins" toast in Initialize() and that requires SendMessage() too.