This is a really odd one... you may want to consider removing the hosts from vcenter and re-adding them.
You can do the following process:
1. Disconnect
2. Remove host
3. Re-add host
4. See if problem goes away
This process will cause your vm's to loose resource pool and rules so you will want to migrate all the vm's off the host before you do this process.
Give it a try and see if it fixes the issue.