DJ Asia -
The "disapearence" of part of the crosshair is actually due to a well known phenomenon - glare. It happens in front of a highly reflective, usually white, image .
If you'd like to see a good example, see :
http://archives.gov/media_desk/press...challenger.jpg
(It's way too big to post here - look what happens to the crosshairs in front of the clouds. )