Compiler error on new project

I have newly installed Unity 5 using its downloader and this is a new project I'm working on. It has only one script. Things I've tried:

• Looking at other answers (none of them helped much)

• Rebooting

• Creating a new project and testing (still the same)

• Deleted the script, created a new one

• Making sure the script name matches 100%

• Saving, reopening

I've literally created a new script and it still gives me the error "No MonoBehaviour script in the file, or their names do not match the file name." When I try to drag it to an object it says "Please fix compile errors before creating new script components". and also .

Oh and the compiler errors:

Could not start compilationWin32Exception: ApplicationName='"E:\'Stuff'\Unity\Editor\Data\Mono\bin\mono.exe"', CommandLine='"E:\'Stuff'\Unity\Editor\Data\Mono\lib\mono\unity\smcs.exe" @Temp/UnityTempFile-087fc7abaf20b5046ae6df41b05f1576', CurrentDirectory='E:/'Stuff'/Unity/Projects/Dave/Assets/..' System.Diagnostics.Process.Start_noshell (System.Diagnostics.ProcessStartInfo startInfo, System.Diagnostics.Process process) System.Diagnostics.Process.Start_common (System.Diagnostics.ProcessStartInfo startInfo, System.Diagnostics.Process process) System.Diagnostics.Process.Start () (wrapper remoting-invoke-with-check) System.Diagnostics.Process:Start () UnityEditor.Utils.Program.Start () (at C:/buildslave/unity/build/Editor/Mono/Utils/Program.cs:33) UnityEditor.Scripting.Compilers.MonoScriptCompilerBase.StartCompiler (BuildTarget target, System.String compiler, System.Collections.Generic.List`1 arguments, Boolean setMonoEnvironmentVariables) (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/MonoScriptCompilerBase.cs:31) UnityEditor.Scripting.Compilers.MonoScriptCompilerBase.StartCompiler (BuildTarget target, System.String compiler, System.Collections.Generic.List`1 arguments) (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/MonoScriptCompilerBase.cs:18) UnityEditor.Scripting.Compilers.MonoCSharpCompiler.StartCompiler () (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/MonoCSharpCompiler.cs:43) UnityEditor.Scripting.Compilers.ScriptCompilerBase.BeginCompiling () (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/ScriptCompilerBase.cs:47)

Compilation failed because the compiler couldn't be executed!