"Invalid XML. Code 4; you should close the plug-in and remove it from any insert before trying to use it again"
This error message has to do with a corrupt or invalid Authorization file. Make sure you are using the latest version of SoundSoap 2 since changes made in the SoundSoap 2.2 update address some issues with authorization.
Some anti-virus /anti-spyware programs can hide or change the System information needed to authorize BIAS SoundSoap 2.1. Make sure that you are not using any such anti-virus software when attempting to authorize BIAS SoundSoap 2.1.
If you are not running any anti-virus software and you are still getting errors and/or you are not able to authorize your BIAS software please contact BIAS Customer Support.