Xinod, grazie al tuo suggerimento ho risolto alcuni dei mie problemi relativi all'utilizzo di più scripts.

Purtroppo però quello relativo alla scomparsa/visibilità di un div continua a darmi problemi.
Se questo è lo script originale
Codice PHP:
<script type="text/javascript">
/************************************************************************************************************
(C) [url]www.dhtmlgoodies.com,[/url] November 2005

This is a script from [url]www.dhtmlgoodies.com.[/url] You will find this and a lot of other scripts at our website.    

Terms of use:
You are free to use this script as long as the copyright message is kept intact. However, you may not
redistribute, sell or repost it without our permission.

Thank you!

[url]www.dhtmlgoodies.com[/url]
Alf Magne Kalleland

************************************************************************************************************/

var dhtmlgoodies_slideSpeed = 10;    // Higher value = faster
var dhtmlgoodies_timer = 10;    // Lower value = faster

var objectIdToSlideDown = false;
var dhtmlgoodies_activeId = false;
var dhtmlgoodies_slideInProgress = false;
function showHideContent(e,inputId)
{
    if(dhtmlgoodies_slideInProgress)return;
    dhtmlgoodies_slideInProgress = true;
    if(!inputId)inputId = this.id;
    inputId = inputId + '';
    var numericId = inputId.replace(/[^0-9]/g,'');
    var answerDiv = document.getElementById('dhtmlgoodies_a' + numericId);

    objectIdToSlideDown = false;
    
    if(!answerDiv.style.display || answerDiv.style.display=='none'){        
        if(dhtmlgoodies_activeId &&  dhtmlgoodies_activeId!=numericId){            
            objectIdToSlideDown = numericId;
            slideContent(dhtmlgoodies_activeId,(dhtmlgoodies_slideSpeed*-1));
        }else{
            
            answerDiv.style.display='block';
            answerDiv.style.visibility = 'visible';
            
            slideContent(numericId,dhtmlgoodies_slideSpeed);
        }
    }else{
        slideContent(numericId,(dhtmlgoodies_slideSpeed*-1));
        dhtmlgoodies_activeId = false;
    }    
}

function slideContent(inputId,direction)
{
    
    var obj =document.getElementById('dhtmlgoodies_a' + inputId);
    var contentObj = document.getElementById('dhtmlgoodies_ac' + inputId);
    height = obj.clientHeight;
    if(height==0)height = obj.offsetHeight;
    height = height + direction;
    rerunFunction = true;
    if(height>contentObj.offsetHeight){
        height = contentObj.offsetHeight;
        rerunFunction = false;
    }
    if(height<=1){
        height = 1;
        rerunFunction = false;
    }

    obj.style.height = height + 'px';
    var topPos = height - contentObj.offsetHeight;
    if(topPos>0)topPos=0;
    contentObj.style.top = topPos + 'px';
    if(rerunFunction){
        setTimeout('slideContent(' + inputId + ',' + direction + ')',dhtmlgoodies_timer);
    }else{
        if(height<=1){
            obj.style.display='none'; 
            if(objectIdToSlideDown && objectIdToSlideDown!=inputId){
                document.getElementById('dhtmlgoodies_a' + objectIdToSlideDown).style.display='block';
                document.getElementById('dhtmlgoodies_a' + objectIdToSlideDown).style.visibility='visible';
                slideContent(objectIdToSlideDown,dhtmlgoodies_slideSpeed);                
            }else{
                dhtmlgoodies_slideInProgress = false;
            }
        }else{
            dhtmlgoodies_activeId = inputId;
            dhtmlgoodies_slideInProgress = false;
        }
    }
}



function initShowHideDivs()
{
    var divs = document.getElementsByTagName('DIV');
    var divCounter = 1;
    for(var no=0;no<divs.length;no++){
        if(divs[no].className=='dhtmlgoodies_question'){
            divs[no].onclick = showHideContent;
            divs[no].id = 'dhtmlgoodies_q'+divCounter;
            var answer = divs[no].nextSibling;
            while(answer && answer.tagName!='DIV'){
                answer = answer.nextSibling;
            }
            answer.id = 'dhtmlgoodies_a'+divCounter;    
            contentDiv = answer.getElementsByTagName('DIV')[0];
            contentDiv.style.top = 0 - contentDiv.offsetHeight + 'px';     
            contentDiv.className='dhtmlgoodies_answer_content';
            contentDiv.id = 'dhtmlgoodies_ac' + divCounter;
            answer.style.display='none';
            answer.style.height='1px';
            divCounter++;
        }        
    }    
}
window.onload = initShowHideDivs;


</script> 
ho provato a trasformare l'ultima parte del codice in

Codice PHP:
.
.
.
.
window.onload=function(){initShowHideDivs}

</script> 
per vedere se continua a funzionare, ma così non è.
La cosa strana è che con il tuo suggerimento sono riuscita ad accorpare più scripts sotto un unico window.onload, ma quello sopra non vuole proprio saperne....