This post is over a year old, some of this information may be out of date.
This week a client made me aware that links in the top navigation and in the quick launch (from SharePoint 2010) cannot be opened in a new tab from the Right-Click menu of Internet Explorer. If you try to do it, the option is not available.
If you do it on a regular link, you should get the following Right-Click menu.
If we check the HTML code of a top navigation or quick launch item, you will see that two spans are encapsulated by an anchor tag.
The spans are displayed as block by the corev4 CSS file, and this CSS attribute seems to be causing the problem.
The solution is to display the spans as inline elements instead of block elements. You can add the following CSS code to your master page or custom style sheet to solve the issue.