Office 365 pain.

.Net development got a hit, my usual code to access Excel stopped working when my job switched over to Office365. It compiles okay by when  opening a excel doc your hit with

Unable to cast COM object of type 'Microsoft.Office.Interop.Excel.ApplicationClass' to interface type 'Microsoft.Office.Interop.Excel._Application'. This operation failed because the Query Interface call on the COM component for the interface with IID '{000208D5-0000-0000-C000-000000000046}' failed due to the following error: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)).

Clear as mud, to complicate life a bit more, some of my application run Excel okay.

Fix, sort of: 

    I been compiling the non working apps using CPU x86 to be sure they run on Win 32-bit PCs.

    Win 32-bit isn't used anymore so I compiled it with setting 'Any CPU' and now I'm happy again.