Fatal error at build - "!IsDirectoryCreated(kManageDllsFolder)"

Hi,
I am a Unity and Game development newbie, so please be gentle.
I am generating a Google cardboard game for android.
This morning I was able to build the game no problem.
I added the following line to a script

transform.rotation = Quaternion.AngleAxis(GvrViewer.Instance.HeadPose.Orientation.y, Vector3.up);

since then I get an error when building the game.
“!IsDirectoryCreated(kManageDllsFolder)
UnityEditor.HostView:OnGUI()”

I have tried removing the code, but now still get the error. Any ideas what could be wrong?

Cheers

Kenny

any got any comment on this? I am really stuck.
cheers
Kenny