[imp] issue forwarding mail

[Pouliot Étienne]

Hi all, 

We are currently having an issue forwarding an email that has an inline image in it. When an user try to forward a mail the meet those condition, we get a white page. Here is the result in error.log : 
PHP Fatal error: IMP_Compose::updateAttachment() [<a href='function.updateAttachment'>function.updateAttachment</a>]: The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition &quot;MIME_Message&quot; of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide a __autoload() function to load the class definition in /var/www/horde/imp/lib/Compose.php on line 690, referer: http://courrier.scol.qc.ca/horde/imp/compose.php?actionID=forward&index=20&identity=0&array_index=10&thismailbox=INBOX 

Futhermore, if after I choose "forward", and I try to "previsualise" the picture in the bottom of the compose window, it seems it try to open an empty picture. 

It works well attachement with attachement that are not inline image. 

We are using IMP 4.0.5 and Horde 3.0.5 

Here is how if vfs is configured : 
/horde/conf.php 
$conf['vfs']['params']['vfsroot'] = '/tmp'; 
$conf['vfs']['type'] = 'file'; 
/imp/conf.php 
$conf['compose']['use_vfs'] = true; 

Any idea what could I do to solve that issue ?