If you run git and then go back to a stable version you may encounter problems, because the stable version cannot understand the new config. So if you have done that, you need to clean you config and create a new one. First, close all Gajim instances and then
In Windows 2000/XP
Start → Run and type
and press Enter
Now locate the config file and remove it and launch the application. A new config file will be created (you need to set accounts and other settings from scratch).
Running both: Stable and GIT
OK. That is also possible but you should avoid mixing the config file.
./launch.sh -p git -s
This creates a config.git (e.g. profile git) and completely separates databases and plugins.