Once you update Windows XP to SP1, when you press Switch Identity on the Outlook Express File menu, select a new identity, and press OK, the main identity is opened instead of the selected identity.
To workaround this 'feature':
1. On the Outlook Express File menu, press Identities and press Manage Identities.
2. Clear the Use this identity when starting a program check box.
3. Press Close.
NOTE: Using this tip will cause Outlook Express to prompt you to select an identity when it starts. Unfortunately, you will be prompted twice.