You mentioned that the error occurs when you try to paste. Can you try different applications and see what happens? If it's an error when you paste, I don't think it could be a SwordSearcher issue, since by that time SwordSearcher is done copying to the clipboard.
Try pasting into Notepad and Wordpad and see what happens and let me know.
Also, regardless, a possible work-around would be to go to File > Preferences > Misc. Options and enable the "Use plain text for clipboard" option.