I recently installed 64-bit Cygwin along side of my 32-bit Cygwin
installation, and find that all the menus show math symbols rather
than text, making LyX unusable.  Note that if I specify a file on the
command line, the contents show up fine - it's just the menus/toolbars
that are unreadable.  This problem does not happen under 32-bit
Cygwin.