New Post: Failure after new install

Installed store version 2.3.8 rel 3 into a new (dev) site v7.2.2 using Hammerflex skin (A responsive DNN skin using Bootstrap 3. v 0.1.0).

Get this error when I try to add the backoffice module to a page:
"Error: NB_Store_BackOffice is currently unavailable. DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at NEvoWeb.Modules.NB_Store.Upgrade.DoUpgrade(Int32 PortalID, String StoreInstallPath, Int32 UserId) at NEvoWeb.Modules.NB_Store.MenuManager.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---"

and this error when I try to add order history module to another page:
"A critical error has occurred. Could not find a part of the path '{myDrive}:\sitePath}\DesktopModules\NB_Store\xml\MainMenu.xml'."

Any ideas on what has happened would be appreciated.

cheers
MartyNZ