This is because the curly quote marks got mangled by the forum parser.
Try the following Find/Replace with "Use wildcards" ON. To enter curly quote marks in the Find What or Replace With box, you have to copy each from the document window through Ctrl+C, then paste them into the Find What or Replace With box with Ctrl+V.
A curly LEFT DOUBLE QUOTATION MARK is inserted into the document window through "Alt+X, 8220".
A curly RIGHT DOUBLE QUOTATION MARK is inserted into the document window through "Alt+X, 8221".
Unfortunately, Word (2007) cannot search for Unicode numbers when "Use wildcards" is ON. And the "Alt+X" method does not work well within the Find What box. You need to copy/paste the curly quote marks from the document window.
Find What: "^034"["^034"]
Replace With Italic Font Format: "\1"