Internal compiler error.

Internal compiler error. See the console log for more information. output was:
Unhandled Exception: System.UnauthorizedAccessException: Access to the path “C:\Users\Public\Documents\Unity Projects\Database\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 <filename unknown>:0 

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

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

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

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

  at Mono.CSharp.SymbolWriter.WriteSymbolFile () [0x00000] in <filename unknown>:0 

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

  at Mono.CSharp.Driver.Compile () [0x00000] in <filename unknown>:0 

  at Mono.CSharp.Driver.Main (System.String[] args) [0x00000] in <filename unknown>:0 

I get this error every time I try to build a project, has anyone encountered this before? If so please post your fixes.
Thanks.

EDIT:
While this error is in my console unity wont recompile any of my scripts. :confused:

Exactly the same problem, after RCA, turned out to be Macfee real time scanning.
For future reference im using windows 8.1 x64 and after disabling the above feature and reopening the project was all ok…

Ok… a work around I have found is using ‘Run as administrator’ on windows 7 - I will compile an error report to send to unity.