Unity3D flash compiler errors when compiling from C#

My project runs fine when I compile for iPhone, Android, Windows and OSX builds but for Flash I get the following errors and warnings:

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(115): col: 24 Error: Call to a possibly undefined method Round through a reference with static type Class.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(15): col: 27 Error: Type was not found or was not a compile-time constant: Random.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(15): col: 40 Error: Call to a possibly undefined method Random.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(15): col: 40 Error: Call to a possibly undefined method Random.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(5): col: 15 Error: Definition System:Random could not be found.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\ContrastStretchEffect.as(98): col: 120 Warning: Migration issue: * is not a dynamic class. Instances cannot have members added to them dynamically.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\ScoreInst.as(18): col: 32 Error: Type was not found or was not a compile-time constant: Stopwatch. public var ScoreInst$timer$: Stopwatch = new Stopwatch().Stopwatch_Constructor();

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\ScoreInst.as(18): col: 48 Error: Call to a possibly undefined method Stopwatch.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\ScoreInst.as(3): col: 27 Error: Definition System.Diagnostics:Stopwatch could not be found.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Meteormaker.as(3): col: 15 Error: Definition System:Random could not be found.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\UpgradeBar.as(55): col: 129 Warning: Migration issue: * is not a dynamic class. Instances cannot have members added to them dynamically.

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\PlayerAvatar.as(58): col: 30 Error: Call to a possibly undefined method PlayerAvatar_Constructor through a reference with static type global:PlayerAvatar.

Error building Player: Exception: Compiling SWF Failed: Loading configuration file C:\Program Files (x86)\Unity\Editor\Data\PlaybackEngines\flashsupport\BuildTools\flex\frameworks\flex-config.xml

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(115): col: 24 Error: Call to a possibly undefined method Round through a reference with static type Class.

          $num =

Number(_Math.Round(Number($num), 0)); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(15): col: 27 Error: Type was not found or was not a compile-time constant: Random.

      public static var rand: Random = new

Random().Random_Constructor(); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(15): col: 40 Error: Call to a possibly undefined method Random.

      public static var rand: Random = new

Random().Random_Constructor(); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(15): col: 40 Error: Call to a possibly undefined method Random.

      public static var rand: Random = new

Random().Random_Constructor(); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Interpolation.as(5): col: 15 Error: Definition System:Random could not be found.

  import System.Random;

               ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\ContrastStretchEffect.as(98): col: 120 Warning: Migration issue: * is not a dynamic class. Instances cannot have members added to them dynamically.

                  (this.ContrastStretchEffect$adaptRenderTex$.elements[$i]

as RenderTexture).Object_hideFlags_HideFlags = HideFlags.HideAndDontSave; ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\ScoreInst.as(18): col: 32 Error: Type was not found or was not a compile-time constant: Stopwatch.

      public var ScoreInst$timer$:

Stopwatch = new Stopwatch().Stopwatch_Constructor(); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\ScoreInst.as(18): col: 48 Error: Call to a possibly undefined method Stopwatch.

      public var ScoreInst$timer$:

Stopwatch = new Stopwatch().Stopwatch_Constructor(); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\ScoreInst.as(18): col: 48 Error: Call to a possibly undefined method Stopwatch.

      public var ScoreInst$timer$:

Stopwatch = new Stopwatch().Stopwatch_Constructor(); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\ScoreInst.as(3): col: 27 Error: Definition System.Diagnostics:Stopwatch could not be found.

  import System.Diagnostics.Stopwatch;

                           ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Meteormaker.as(26): col: 35 Error: Type was not found or was not a compile-time constant: Random.

      public var Meteormaker$m_rand$:

Random = new Random().Random_Constructor_Int32(452); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Meteormaker.as(26): col: 48 Error: Call to a possibly undefined method Random.

      public var Meteormaker$m_rand$:

Random = new Random().Random_Constructor_Int32(452); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Meteormaker.as(26): col: 48 Error: Call to a possibly undefined method Random.

      public var Meteormaker$m_rand$:

Random = new Random().Random_Constructor_Int32(452); ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\Meteormaker.as(3): col: 15 Error: Definition System:Random could not be found.

  import System.Random;

               ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\UpgradeBar.as(55): col: 129 Warning: Migration issue: * is not a dynamic class. Instances cannot have members added to them dynamically.

          ($transform.Component_gameObject.GameObject_GetComponent$1$1(MeshRenderer.$Type)

as MeshRenderer).Renderer_enabled_Boolean = true; ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\UpgradeBar.as(56): col: 130 Warning: Migration issue: * is not a dynamic class. Instances cannot have members added to them dynamically.

          ($transform2.Component_gameObject.GameObject_GetComponent$1$1(MeshRenderer.$Type)

as MeshRenderer).Renderer_enabled_Boolean = true; ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\UpgradeBar.as(86): col: 129 Warning: Migration issue: * is not a dynamic class. Instances cannot have members added to them dynamically.

          ($transform.Component_gameObject.GameObject_GetComponent$1$1(MeshRenderer.$Type)

as MeshRenderer).Renderer_enabled_Boolean = false; ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\UpgradeBar.as(87): col: 130 Warning: Migration issue: * is not a dynamic class. Instances cannot have members added to them dynamically.

          ($transform2.Component_gameObject.GameObject_GetComponent$1$1(MeshRenderer.$Type)

as MeshRenderer).Renderer_enabled_Boolean = false; ^

E:\meteormania\Temp\StagingArea\Data\ConvertedDotNetCode\global\PlayerAvatar.as(58): col: 30 Error: Call to a possibly undefined method PlayerAvatar_Constructor through a reference with static type global:PlayerAvatar.

          return new

PlayerAvatar().PlayerAvatar_Constructor();

                                   ^

Among a few other errors and warnings. Any ideas why and how to fix?