How do I find affected segment for "Internal error: Multiple tags with the same ID 'Bold' have different start tag properties"

How do I find the segment which causes the error message "Internal error: Multiple tags with the same ID 'Bold' have different start tag properties"? I have translated a large amount of text since last saving the file, so would need to know how to find the segment in which the error lies.

BTW, I don't have the option (suggested elsewhere) of starting anew with the source file and filling it from the TM as I am working online in GroupShare with files on the client's server.