As noted in comments above, the OP’s code generates malformed CSS. Per request, here is corrected code. It should help solve part of the issue (or prevent other issues) but I doubt it solves all of it.
function blog_link_genesis() {
if( is_single() || in_category('investors') || is_page( array(4, 30))) {
$current="#header #nav #menu-item-133 a"; ?>
<style type="text/css">
<?php echo $current; ?> { color: #ff0;}
</style><?php
}
}
add_action( 'genesis_header' , 'blog_link_genesis' );
All you really needed to do was roll the whole block of code into the if.
I suspect that you have an XY problem in this question. If you were to explain the problem and the desired result better, I suspect that there is a better way to approach this.
If the menu you mean is this one with “Trials”, “Cloud Services”, “Bright Eval”, etc. then that looks like a standard WordPress menu. If you look at the markup, you will notice a number of useful classes. To add more you want to hook into nav_menu_css_class something like what is done here.