Is this something that started happening recently? We have seen similar things starting about 1-2 weeks ago after a Windows update, but only some specific laptops, and it was not just affecting BASS but any recording application (e.g. Audacity). Turning off sound enhancements in Windows or not using the built-in audio device of the laptop supposedly fixed it for them. If that sounds similar to what your users are experiencing, maybe one of them could try and see if they have the same problem in an application like Audacity. If they do, it's a Windows or driver issue.