[MrApples]

Ok, I did that. My code exactly for that...

var hcur='logo';
function switchheader(id){
	alert('runs! id:' + id + ' hcur:' + hcur);
	if ( hcur != id ){
	alert('1');
		document.getElementById(hcur).style.display = 'none';
		alert('2');
		document.getElementById(hcur + 'b').src = '/styles/7M-v1/new/hb_' + hcur + '.png';
		alert('3');
		document.getElementById(id).style.display = '';
		alert('4');
		document.getElementById(id + 'b').src = '/styles/7M-v1/new/hb_' + hcur + '_alt.png';
		alert('5');
		if (hcur == 'logo'){
		alert('6');
			document.getElementById('logo2').style.display = 'none';}
			alert('7');
		if (id == 'logo'){
		alert('8');
			document.getElementById('logo2').style.display = '';}
			alert('9');
		hcur = id;
		alert('10');
	}
}

Apparently it is stopping at

		document.getElementById(hcur + 'b').src = '/styles/7M-v1/new/hb_' + hcur + '.png';

Does JS lack failsafe checking? That image does not exist (haven't gotten to that yet), so is it just killing the function over it? Thank you a lot for this error finding command by the way.

PS: THe problem defiantly lies in those 2 lines, I commented them out and it works.