Chairside is a client education program (think CAESY cloud). If computers are unable to access, check the following:
Log onto Chairside computer, and click on the Chairside link on desktop. Then hit restart
If that did not fix it, then go to task manager, and end task NetworServer.EXE and re-open Chairside
If that did not work, open up SQL Server manager and go to SQL Server 2005 Services, and then make sure the SQL Server (SQLEXPRESS) is running, if it is not, then start it and clients should work now.