DynamicAccounting.net: Error Restoring SQL Database

Ian Grieve looks at an Error Restoring SQL Database

$Restore failed for Server. (Microsoft.SqlServe.SmoExtended) Additional information - System.Data.SqlClient.SqlError: Directory lookup for file "e:\SQL Server\Data\GPSGPNLDat.mdf" failed with the operating system error 3(failed to retrieve text for this error. Reason 15105). (Microsoft.SqlServer.Smo)$