When using a Remote Users Collection and migrating mailboxes to the target Exchange 2010 the MSA needs to delete and then to create the mailbox, and the MSA might report the following.
8/4/2011 10:50:38 AM CExchAdmin::SetMailboxInfoE2K TraceMsg 4702 Creating mailbox '/o=CITS/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=User1'.
8/4/2011 10:50:38 AM CExchAdmin::SetMailboxInfoE2K Error -2147023495 SetMailboxInfo failed Invalid menu handle. File: 'errors.hpp' Line: '292' File: 'aeExchAdmin2K.cpp' Line: '106'
8/4/2011 10:50:38 AM CMBMCopier::CopyMailbox TraceMsg 6132 Cannot copy mailbox '/o=WUSM Org/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=User1'.