To reproduce:
- Open attached project
- Go to File > New Project
- Observe the following error messages in Console:

Failed running AssemblyUpdater.exe its output was: (-4) System.UnauthorizedAccessException: Access to the path "C:\Program Files (x86)\Unity_5.0.0a1\Editor\Data\UnityExtensions\Unity\GUISystem\5.0.0\Editor\UnityEditor.UI.dll" is denied.
at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0
at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share) [0x00000] in <filename unknown>:0
at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare)
at System.IO.File.Open (System.String path, FileMode mode) [0x00000] in <filename unknown>:0
at AssemblyUpdater.Core.AssemblyUpdaterContext.ReadAssembly (System.String assemblyPath, System.String[] searchPaths) [0x00000] in <filename unknown>:0
at AssemblyUpdater.Core.AssemblyUpdaterContext.From (System.String assemblyPath, System.String[] assemblySearchPaths, UpdaterMode mode, IAssemblyUpdaterListener listener) [0x00000] in <filename unknown>:0
at AssemblyUpdater.Application.Program.CheckForObsoleteAPIUsage (AssemblyUpdater.Application.CommandLineSpec config) [0x00000] in <filename unknown>:0
at AssemblyUpdater.Application.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0

UnityEditor.Scripting.AssemblyUpdaterHelper:DoesAssemblyRequireUpgrade(String)

System.UnauthorizedAccessException: Access to the path "C:\Program Files (x86)\Unity_5.0.0a1\Editor\Data\UnityExtensions\Unity\GUISystem\5.0.0\Editor\UnityEditor.UI.dll" is denied.
at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0
at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share) [0x00000] in <filename unknown>:0
at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare)
at System.IO.File.Open (System.String path, FileMode mode) [0x00000] in <filename unknown>:0
at AssemblyUpdater.Core.AssemblyUpdaterContext.ReadAssembly (System.String assemblyPath, System.String[] searchPaths) [0x00000] in <filename unknown>:0
at AssemblyUpdater.Core.AssemblyUpdaterContext.From (System.String assemblyPath, System.String[] assemblySearchPaths, UpdaterMode mode, IAssemblyUpdaterListener listener) [0x00000] in <filename unknown>:0
at AssemblyUpdater.Application.Program.CheckForObsoleteAPIUsage (AssemblyUpdater.Application.CommandLineSpec config) [0x00000] in <filename unknown>:0
at AssemblyUpdater.Application.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0

UnityEditor.Scripting.AssemblyUpdaterHelper:DoesAssemblyRequireUpgrade(String)