Forticlient on PC breaks network and high CPU

[TysonIT]

We had an event this week, which seamed to start late one afternoon and lasted until we removed Forticlient from all the PC's.  However when I put forticlient back on a test pc to try and recreate the issue the problem went away.

We have FG 600D firewalls, switches and EMS running. All the OSX clients with Forticlient were fine. VPN connected forticlients from external also worked fine. Once we unregistered then shutdown forticlient the issue went away, so we uninstalled forticlient and pushed it back with VPN only.

I don't like that this "fixed" it without knowing why this happened and can't seam to reproduce it on a test PC. Anyone else see this recently?

[garyxd]

There is a known issue in FortiClient 5.2 and FortiClient 5.4.0 GA where a multicast flood condition can occur when the Application Firewall feature is enabled.  I don't have the bug number, but this will supposedly be fixed in 5.4.1.  Also is fixed in interim build 5.4.0 build 830 (which is around on this forum).  I had a FortiClient deployment bring down a medium sized business three days in a row due to 100% cpu issue and enough multicast to lock up the core switches.  Awesome bug...