I have a single subnet network that consists of two buildings. One building has a has a Netgear FS726T Smart switch and the other has a Netgear FS750T2 Smart switch. The two switches are connected by fiber. The server on the network is a Windows 2008 SBS which hosts the DNS and DHCP servers. This setup has worked fine for the past five years. Suddenly, yesterday, five computers where not able to connect to the servers, internet etc. I tried restarting all the equipment with no success. This morning, they are suddenly able to connect again. However, there are still communication issue between some computers. For example, I am not able to ping some of the computers in building two but I am able to ping my computer from those machines. I am at a loss as to what to check. Any suggestions?