Hi Nigel,
Luckily the switch has many things going for it.
1. It's a managed switch and you can set switch ports and associated PCs and Servers and switched ports to fixed speeds rather than autonegotuiate link speeds. This would remove auto negotiation of speed and duplex issues.
2. It has a tremendous warranty and you have the ability to speak to a human that can help diagnose if the switch is working well or not.
Why not avail yourself of the wonderful hard working folks at our small business support centers and call or " click to chat."
http://www.cisco.com/en/US/support/tsd_cisco_small_business_support_center_contacts.html
Regards Dave