Error when importing certain assets packs (like water(pro))

Does anyone have an idea why I keep getting this error when I import certain assets such as water(pro) and the new Unity standards assets(beta) bundle? Any help would be much appreciated. I always get "CSharp-firstpass.dll.mdb" is denied.", and I don't think there is anything else I could pay for, except knowledge. :-)

DrCalderone

Internal compiler error. See the console log for more information. output was: Unhandled Exception: System.UnauthorizedAccessException: Access to the path "G:\UnityProjects\Saturdaythe5thApril2D\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