Issues when using Adobe Media Server with multicast

We are using Adobe Media Server 5 with Multicast, we have partnered with INXPO for our Multicasting needs, and our multicast network runs over Avaya VSP hardware and are experiencing the following issues,

1. When users are watching the multicast stream, they will experience  a brief period during which audio and video will freeze, however will then recover.  We are seeing this issue whether the user is using IE or Chrome.  This may be a flash related issue, during this time the user is still receiving the multicast stream, however the content is freezing on a consistent basis. We have established QOS related rules for this and are not seeing any bandwidth or network related issues during the issue.

2. The AMS service will stop working intermittently, at times users will report that they are not able to see or hear any audio. When looking at the Adobe Streaming server (this is running on Win 2012 Server) under resource monitor, we will see that the AMS.CORE service will not be receiving or sending data.  This necessitates have to stop and restart the AMS service on the server. The multicast stream will then be available for users. It appears the service is crashing, however there are nothing in the event log stating the reason.

Our client PCs are currently running flash 25.0.0.148

Please advise as to suggestions for troubleshooting, and what can be done to resolve this issue