This is the first of a two-part column. The second part will appear Tuesday.Trying to nail down a breach of fiduciary duty claim against Stefan G. Zimmerman — president, director and majority shareholder of Our Wood Loft Ltd. — OWL’s minority shareholders, Jeffrey Roberts and John Jossund, hired Loyola University School of Law Professor Charles W. Murdock to present expert testimony on commercial customs and industry standards. But a DuPage County judge ruled the professor was offering improper opinions …