Getting error that Network is not connected during mail box migration. (NETIQKB71229)

When migrating a mail box from Exchange 2003 to Exchange 2007 the migration fails and an error is presented stating that the network is not connected, even though it is. You are then prompted to choose to enter recovery mode or not.
Failed to fetch email format for source information [HR=0x800700ea]

A fatal error has occurred. The migration will be aborted. [HR=0x800700ea]

There are two possible resolutions for this issue:

1. Create a forest level trust between the source and target domains.
2. Close and re-open the console.

Or

You can provide source Microsoft Exchange server credentials for the Move-Mailbox PowerShell cmdlet using the Source Credentials window of the Specify Migration Options wizard and migrate mailboxes without establishing a forest trust between the source and target domains.  To do this follow the below documented process, from the release notes:

To access the Source Microsoft Exchange Server Credentials window:

1. Click Start > Run.
2. In the Open field, type Regedit, and then click OK.
3. In the left pane, browse to HKEY_LOCAL_MACHINE\SOFTWARE\NetIQ\ExchangeMigrator.
4. On the Edit menu, select New, and then click DWORD Value.
5. Type ShowDialog, and then press Enter.
6. In the right pane, double-click ShowDialog . The Edit DWORD Value dialog box is displayed.
7. Select Decimal.
8. In the Value data field, change the value from zero (0) to one (1).
9. Click OK, and then close the Registry Editor.
10. To access the Source Microsoft Exchange Server Credentials window, restart NetIQ Exchange Migrator.

To use the credentials in the Source Microsoft Exchange Server Credentials window:

1. Click Start > Run.
2. In the Open field, type REGEDIT, and then click OK.
3. In the left pane, browse to HKEY_LOCAL_MACHINE\SOFTWARE\NetIQ\ExchangeMigrator.
4. On the Edit menu, select New, and then click DWORD Value.
5. Type UseMoveCredential, and then press Enter.
6. In the right pane, double-click UseMoveCredential. The Edit DWORD Value dialog box is displayed.
7. Select Decimal.
8. In the Value data field, change the value from zero (0) to one (1).
9. Click OK, and then close the Registry Editor.
10. To use the credentials in the Source Microsoft Exchange Server Credentials window, restart NetIQ Exchange Migrator.

 

This is caused by not having a forest level trust established between the source and target domains.

Formerly known as NETIQKB71229

Warning
Be careful when editing your Windows Registry. If there is an error in your Registry, your computer may become nonfunctional. If an error occurs, you can restore the Registry to its state when you last successfully started your computer. For more information, see the Help for the Windows Registry Editor.