The network runs slow; processes fail; users cannot access servers or other devices

Broadcast storms may be occurring in the network. These may be caused by redundant links between nodes.

If you are configuring a port trunk, finish configuring the ports in the trunk before connecting the related cables. Otherwise you may inadvertently create a number of redundant links (that is, topology loops) that will cause broadcast storms.
Turn on STP to block redundant links
Check for FFI messages in the Event Log