Hello, I confirm the solution from Daniel. I am upgrading from Lenny to Squeeze. I already had open-vm installed on Lenny. After upgrading, I ran :
*module-assistant auto-install open-vm -i * to build the modules for Squeeze's stock kernel and got the same errors as mentionned here Doing : *module-assistant clean open-vm* then again : *module-assistant auto-install open-vm -i* and enjoy ;)
