Hi celuch,
This usually happens when some whitespace or other content has been added to the CMSB files or plugins. This can happen if you upload the files in ASCII mode (and it converts the line-end chars from windows/mac/linux and back and everything gets double spaced). Or if you've got content or whitespace in any of your plugins.
Does the error say "Output started in [file] on [line]"? That would be where it thinks the extra content or whitespace was added.
I'd try re-uploading the CMSB files and ensuring your FTP client is using "Binary Mode" for uploads and/or checking the file/line mentioned in the error.
Hope that helps! Let me know what happens.
Dave Edis - Senior Developer
interactivetools.com