When using forms
authentication, a workflow will pass only the username, not the entire
string required to assign a task to someone. For example, if your
Membership Provider is called "memprovider" and your username is
"usera" then you could assign a task to yourself by entering
memprovider:usera in the "Assigned To" field. A workflow will only pass
"usera" which isn't enough in a workflow to assign a task. To work
around the problem, create a workflow in Visual Studio that
concatenates the membership provider name and the username.