Without your style_xyz_ie6.css in IE6, your form is shifted about 250px to the right and all the input fields are selectable. This sheets must contain the problem.
In style_lt_ie6.css I looked for:
#ER-content { /* .. Here you have multiple problems */ }
position absolute means in relation to the parents position. If the parent (#ER_template), - and his parent and so on - isn’t explicitely positioned (relative? absolute?) the rendering result is probably not, what you wanted.
Then, IE often doesn’t like negative margins .. and you used negative margins instead of a combination of top|left|bottom|right.
What follows is not the solution. Its just one plant in a jungle, but try this
body, #ER_template { position:relative }
#ER-content { position: relative; margin: 0; }
and see what happens.
:)