AgentTicketFreeText action Error modifying ticket freetext

[StefanoBoccanera]

Hi

I'm getting an error while I'm trying to modify some ticketfreetext from AgentTicketFreeText form (folowing from source page)

<form action="/otrs/index.pl" method="post" enctype="multipart/form-data" name="compose" id="Compose" class="Validate PreventMultipleSubmits"><input type="hidden" name="ChallengeToken" value="2bcecb71f203e8782668410bc7533860"/><input type="hidden" name="ChallengeToken" value="2bcecb71f203e8782668410bc7533860"/>
<input type="hidden" name="Action" value="AgentTicketFreeText"/>
<input type="hidden" name="Subaction" value="Store"/>
<input type="hidden" name="TicketID" value="48"/>
<input type="hidden" name="Expand" id="Expand" value=""/>
<input type="hidden" name="FormID" value="1321382453.7313245.81260394"/>
<input type="hidden" id="ImpactRC" name="ImpactRC" value="0"/>
<input type="hidden" id="PriorityRC" name="PriorityRC" value="0"/>

I changed some freetext, then after pressing the Accept button, the browser show a box requesting to download index.pl (see attach).

Also I cancel the popup or don't confirm the operation, the changes are applied (good for me) but the problem could be the agent in error.

Any suggestion about the cause ?

best regards

stefano