Omni 7800 Problems VRRP-STP

[orobledillo]

Hi,

I've a issue with a cuple OmniSwitch 7800 how CORE funcions with continous lost of service.
I think that topology is simple.
The 7800 interconnected with link aggration with two static 1G fiber physical ports. These are run VRRP CORE1 release 5.4.1.563 role primary and CORE2 release 5.4.1.464 role secondary.
These have interconnected several sw family 6600 with a unique physical port each core switch, as well as, a cuple family 6850 with a link aggregation formed with two 1Gb physcal ports.
All topology runs stp 1x1.

Several times, we have experimented lost of service when when once created static linkaggr4 with two fiber physical port bewteen a new 6850 release 6.4.3.810 and CORE1, we have tried create another identical static linkaggr 7 bewteen CORE2 and the 6850 closing the bucle.
At first, this linkaggr7 in CORE2 show up but a physical port is flapping up/down. Finaly, CORES show vrrp and stp recalculation problems and service is down.

this issue can be possible for different core version?
Do you kwon any bug for link aggregation problem?
What do you think?

Thanks a lot.
Regards.