I changed from multiboxer v2 to jamba, but now people on my friends list cant invite my main character into groups, I will auto join but then I will leave the group again, why is that ? how can I stop that ?
Hmmm. I've never seen that behaviour.

There was a problem just after 3.1 hit the live servers whereby the previous version of Jamba would decline invitations from pretty much everybody, but I've never heard of it automatically leaving a group once joined.

All I can suggest is that you make sure you have the very latest Jamba and go through all the configuration options to make sure they have sensible values (remembering to push the changes to your drones too).

Maybe somebody else can help with that particular problem.