gr8pretender

Hi everyone. I've combed all kinds of different forums searching for an answer and have yet to find a similar case so I guess I'll start the precedent here. Pretty much our situation is that we have classrooms that we occasionally have to clone with Ghost 11, the switches in place in each room are really slow so we bought these new Cisco switches (SG200-50) to deploy the image. Pretty much our issue is at least a 15% of the clients fail every single time. They are giving a "client timed out" error, it freezes up the ghostcast and slows down the whole process, and a lot of the time even 50% end up failing when all is said and done. We can usually unicast/locally clone them when they fail, even through the switch with enough tries. It seems pretty random so we can rule out ports pc problems, all the managed switches and un-managed switches seem to have this problem. I've read several articles about tree spanning and Symantec has said that its because we need to enable IGMP (which one of my co-workers argues has nothing to do with multi-casting) and I'm not the most knowledgable with this kind stuff so I'm just playing middleman between my co-worker and Symantec/Cisco technicians. Anyone have any ideas how we can get little to none of the clients to fail?