try/catch

          try
                {
                    $CS = Get-WmiObject -Class Win32_ComputerSystem    -ComputerName $Computer -ErrorAction Stop
                    $BS = Get-WmiObject -Class Win32_Bios              -ComputerName $Computer -ErrorAction Stop
                    $OS = Get-WmiObject -Class Win32_OperatingSystem   -ComputerName $Computer -ErrorAction Stop
                }
                catch
                {

                   "$(get-date) - $computer failed the wmi call!" | out-file c:\errorlog.txt -Append
                   $error[0].Exception.Message | out-file c:\errorlog.txt -Append
                   break
                }