Hello Sir,
I believe you might do best by calling our support. Here is a link:
http://www.cisco.com/en/US/support/tsd_cisco_small_business_support_center_contacts.html
If you want to check into this a little more, there here are a few thoughts.
The switches do support MSTP. Have you checked for which switch is the root, do all switches agree? You also need to make sure all the configs are the same, native VLANs and allowed VLANs, instance IDs and vlan ranges, etc ...
A "broadcast storm" sounds like you have introduced a loop into the network, all the lights come on, and your network looks like a Christmas Tree. Is this what is happening? If the traffic simply dies, then this might indicate a port mismatch of some kind and the port is getting shut down by either system. Having ports shut down for mismatches is fairly common.
I would suggest placing these switches into your environment one at a time, and then watching to see which switch introduces the problem. Check the configs and make sure everything is compatible.
I would also suggest a call to our support center, as they might be able to answer your questions while you are adding the switches.
HTH,
Andrew Lissitz
