Mail Target Agent or Calendar Synchronization Agent fails with "Logon Error -2147467259 Unspecified. (4325578)

EMWMTA.log or EMWCSA.log shows entries similar to:

4/25/2011 3:12:00 PM CSession::Logon TraceMsg 4800 Logging on to the mailbox '/o=ORG/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=qmm-svc' (Server: 'SERVER', user: 'DOMAIN\qmm-svc', has asocciated PFDB: 'True', connection flags = 0).
4/25/2011 3:12:00 PM CSession::Logon Error -2147467259 Unspecified error File: 'aeMAPIProfile.cpp' Line: '136'

Attempting the same operation manually using MFCMAPI causes MFCMAPI to freeze upon selecting 'Logon and Display Store Table'.

Attempting to view a list of MAPI profiles in MFCMAPI  using '| Profiles | Show Profiles' shows:

Error:
Code: MAPI_E_TABLE_TOO_BIG == 0x80040403

Exporting HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles results in a very large file (4 GB +).