I'd check to ensure that your field rules aren't overlapping, conflicting, or evaluating the same fields multiple times. With that many rules, it might be easier to use JavaScript and CSS to show or hide fields and it's pretty straightforward to do so.

For example, create a single line field and in its Advanced tab, give it the toggle class.

If you wanted to hide this field by default, you could insert this CSS rule on the CSS and JavaScript page:

.toggle {display:none;}

If you wanted to show this field if another field has a certain value, you could do that, too. Let's assume this other field has been given the otherField class.

$('otherField input').blur(function () { //when the user leaves the other field
    if ($('otherField input').val() === 'the value you want') //check its value, if it matches what we want
    {
        $('.toggle').show(); //show the hidden field
    }
    else $('.toggle').hide(); //otherwise, keep it hidden or hide it again
});

If you're new to JavaScript (and jQuery, the library used in my sample code), check out this page in the online help.