When @page is used, Doxygen 1.6.2 fails to generate the HTML page title if an underscore ( _ ) character is used in the tag name.  The title and link with be show correctly if the @ref <tag name> option is used, but it won't display on the actual page.

Example:

@page UPPER_TAG Uppercase tag name with underscore
   Where is my title?

@page UPPERTAG  Uppercase tag name w/o Underscores
   The title is showing.

@page lower_tag  Lower case tag name with underscore
   What happen to the title? 

@page lowertag  Lower case tag name w/o underscore

@mainpage
   - @ref UPPER_TAG    
   - @ref UPPERTAG
   - @ref lower_tag
   - @ref lowertag