Thank you all for your help. The example code is very close to the actual code and the problem is that sometimes, depending on the computer, because of the operator >> to deserialize the style m_pFont, several m_pFont pointed to the same memory area. I studied the problem with a minimal grid ... and finally realized that in my application I was not using this m_pFont. I modified my code so that I would no longer use it at all, destroy it and set it to NULL which definitively resolved my problem. If I don't fully explain the phenomenon, I think it comes from the fact that these m_pFont contained the same data and that the operators << consider the pointer had already been serialized as explained in the TN002: Persistent Object Data Format | Microsoft Docs ... Maybe ... Regards