This could be because of the settings in the managed switch, if it is a cisco switch have you followed the recommended guide to verify the correct settings are enabled?
[url]http://fogproject.org/forum/threads/cisco-programming-guide.10856/[/url]
PLEASE NOTE: I am not a cisco engineer, and I never claimed to be. These settings will work with FOG, if you are familiar with Cisco, please try enabling and disabling settings and documenting the process to share with the rest of us if you find a perfect set up 🙂
This is just a basic installation that will get fog running.
I have had the BEST luck using unmanaged equipment though.