vSphere / ESXi Usernames

When adding users to ESXi 4.1 you can sometimes get the error "User name or password has an invalid format".

This is fixable by checking the following:

• Your password is at least eight characters in length.
• Your password or username entered contained characters outside of the character types allowed.

Allowed characters:

• Numbers, uppercase alphabetic characters, and lowercase alphabetic characters
• Special Characters ~!@#$%^&*()_+{}|:"<>?/.,';\][=-`)