Why does this HAPPEN!

Every time i make a project in unity personal i get this error Unhandled Exception: System.UnauthorizedAccessException: Access to the path "C:\Users\benw\Documents\age of infinity\Temp\Assembly-CSharp-firstpass.dll.mdb" is denied.

at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in :0

at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean isAsync, Boolean anonymous) [0x00000] in :0

at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access) [0x00000] in :0

at Mono.CompilerServices.SymbolWriter.MonoSymbolWriter.WriteSymbolFile (Guid guid) [0x00000] in :0

at Mono.CSharp.SymbolWriter+SymbolWriterImpl.WriteSymbolFile () [0x00000] in :0

at Mono.CSharp.SymbolWriter.WriteSymbolFile () [0x00000] in :0

at Mono.CSharp.CodeGen.Save (System.String name, Boolean saveDebugInfo, Mono.CSharp.Report Report) [0x00000] in :0

at Mono.CSharp.Driver.Compile () [0x00000] in :0

at Mono.CSharp.Driver.Main (System.String[] args) [0x00000] in :0 which i dont know how to fix