The beremote debug log on the exchange server shows:
BEREMOTE: [02/08/11 15:22:44] [1432] [FSYS:ESE07] FindDrives ... This is not an Exchange Server (0)
BEREMOTE: [02/08/11 15:23:31] [1432] AdsiConfiguration::Connect::ADsOpenObject(LDAP://RootDSE) RootDSE-> Failed ... 0x8007054b
While opening the selection list, an LDAP query is called to discover exchange resources .When the server is in a workgroup or a large environment, it's not able to contact the domain controller .
The delay in opening the selection list is caused due to the time out of the LDAP query.
Join the Backup server to a domain if applicable, otherwise this behavior is expected in larger environments.