If you've compiled/re-compiled an ADO application on a Windows 7 Service Pack 1-based computer and the app does not run on down-level operating systems with the any of the error messages below, please see our new KB article published today (16th of March, 2011) :

Error message 1

REGDB_E_CLASSNOTREG (0x80040154)

Error message 2

E_POINTER (0x80004003)

Error message 3

E_NOINTERFACE (0x80004002)

Error message 4

Unable to cast COM object of type 'System.__ComObject' to interface type 'ADODB.Connection'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{00001550-0000-0010-8000-00AA006D2EA4}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).”