I am not familiar with this issue but I looked around and i can see a bugzilla entree that has a solution on this:
https://bugzilla.redhat.com/show_bug.cgi?id=485903
From what i am reading around, it is probably not related to the OFED driver. the fact the iptables service needs to be stopped/start actually trigger the issue.
Anyhow, check the bugzilla page and see if this is matching your issue.