pfSense

Greatings!
We discoverd a problem with pfsense 2.2.x.
We are using Citrix XenServer (V6.2-6.5) in our own company and our customers.
So we have multible XenServer hosts and each of them has multible VMs.

On one of ower XenServer hosts, we only run server for communication services - like ftp, exchange, etc.
One of them was an pfsense 2.1.5 server.
Since upgrading pfsense from V 2.1.x to 2.2.x, other servers on the same host are cut off from the internet.
ICMP (ping) requests to servers in the internet are successfully, but every http call fails.
Firewall and IP Setting are all correct - they have not changed since upgrading.

The strange thing is, all other pcs or servers in our lan (even on other XenServers) are fully functional.

First we thought somthing broke by the updating process. So we installed a new pfsense 2.2 - same behavior.
It could not be a hardware problem, because we can reproduce the same behavior at customer systems.

Currently we rolled back every pfsense installation to 2.1.5, because of this issue.

Thanks help!
Regards!