Just a quick post to make sure everyone is aware, the 'Bad Login' message a lot of players are getting when trying to connect after switching between Minecraft accounts is in fact a Technic Launcher bug that has been around a little while now.
If you get this problem then try completely closing your Technic Launcher and relaunching, if that doesn't work for you then try restarting your computer and if that doesn't work either you will have to 'reset the pack' by using the reset option in the launcher or manually removing your '.technic' folder.
Hope that helps!
