NAV 2009 R2 Classic Client crashes when sending email

INES_BM

Dear ALL,

I am using Microsoft Dynamics NAV 2009 R2 build 6.00.32012.

In one customized form, I try to detect all changes done in the customer record and send a notifcation email containing old and new values.
The concerned function is called in The OnModify trigger.
I use codeunit 400 to prepare and send the email.

Suddenly, the NAV classic client crashes when the user modify any record, on one post using Windows 8.1. (Please find attachement for the error message)
Today, the problem appear with the users logged in remote desktop server (Windows Server 2008 R2).

Your suggestions would be so helpful.
Thank You