This means you probably edited manually the
bug-tracking.conf files and included plain text passwords.
This is important to NEVER edit manually those files as all passwords fields must be encrypted by XStudio. If you edit manually a password you make the complete file corrupted and unreadable by XStudio.
To get back to a normal situation, edit manually (yes, that's an exception!) the file and give the following value for all the passwords you manually edited:
0102030405060708A1A2A3A4A5A6A7A8. This of course corresponds to a wrong password but will make the configuration file valid again and XStudio will make you possible to change this password later through its GUI interface.