Warning when translating

Hi, I get this message

Warning: The actual translation loaded content contains mixed textdomains and is not pure translateable textdomain within them.
It seems, that there is code contained Extracted out of other plugins, themes or widgets and used to copy & paste inside some source files.
The affected are unknown textdomains: wordpress-importer 

I do not explain at all the installed theme

What can I do to not fumble in php files?
Wordprss importer gone.

Best regards and thanks for plagin

http://wordpress.org/extend/plugins/codestyling-localization/