After working without issue, now when trying to open project pages "Not Responding" is displayed in the title bar for several minutes, and eventually a timeout error message is displayed. The page eventually opens.
Internal ErrorError Message: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.TargetSite: Boolean CheckConn(System.Data.SqlClient.SqlException)DeclaringType: ECT.ECAD.DAL.SqlServerProjectAttributes: privateMemberType: Method
In a particular case, a colleague was able to open the same pages without issue, indicating the problem was not related to the file server or SQL Server themselves. Rebooting the workstation did not help. Renaming the user application data folder only allowed the software to start faster since no project had focus, but the problem opening pages persisted. A virus scan revealed several instances of suspect software. Cleaning these resolved the issue.