Notifi conflict with Panel Search extension

Hi,
I have an extension/add-on to my V1.1.10 installation called PanelSearch which puts a search box in the side panel. It's a slightly modified version of an example I found in the Vanilla documentation somewhere and is fairly simple - not a lot to it. However, it's causing some problems with Notifi 2.0.4 that I've just installed. If I disable PanelSearch, Notifi works perfectly, but with PanelSearch enabled it causes a search to be executed when a comment is added to a discussion. The search returns no results leaving the user who attempted to post a comment with a blank content area on the page (Vanilla header and side panel are still visible) and the comment fails to be added. This is what the browser requests after a comment is submitted:

http://forum.mysite.com/search.php?PostBackAction=Search&Type=Comments&Keywords=&FormPostBackKey=bb6405ec3fb9321a53d938e5d94ef4e5&CommentID=0&DiscussionID=8&PostBackAction=SaveComment&UserCommentCount=0&AuthUserID=0&Body=Test&FormatType=Text

Here is the code inside default.php for PanelSearch (the only file apart from css for the extension):

if (in_array($Context->SelfUrl, array('index.php','comments.php','categories.php')))
//if ($Context->SelfUrl == "index.php")
{
   $Context->Dictionary['Search'] = 'Search';

   // Create my search form
   $SearchForm  = '<div id="PanelSearch">';
   $SearchForm .= '<form method="get" action="search.php">';
   $SearchForm .= '<input type="hidden" name="PostBackAction" value="Search" />';
   $SearchForm .= '<input type="hidden" name="Type" value="Comments" />';
   $SearchForm .= '<input type="text" name="Keywords" class="PanelInput" />';
   $SearchForm .= '<input type="submit" class="PanelSearchButton" value="'.$Context->GetDefinition('Search').'" />';
   $SearchForm .= '</div>';

   // Add the form to the panel
   $Panel->AddString($SearchForm);

   // Add the style to the head
   $Head->AddStyleSheet("extensions/PanelSearch/style.css", "screen"); 

Any ideas as to what may be causing the conflict with Notfi?