I did some research and found this:

Disabling Fast User Switching in Windows Vista

Click Start, type GPEDIT.MSC and press Enter
Go to the following location:

Local Computer Policy | Administrative Templates | System | Logon

Set the Policy Hide entry points for Fast User Switching to Enabled
Quit the Group Policy Editor.

By enabling the policy, Administrators hide the Switch user button in the
Logon UI, the Start menu and the Task Manager. Note that the Group Policy
Editor does not exist in certain editions of Windows Vista. Alternately, you
can configure the setting via the registry.



"Lang Murphy" wrote:
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> Downloaded all headers. Searched on "user switching" and found two posts
> from a while back... (also checked admin_accts_pws NG... no luck there
> either)
>
> Anyone know how to disable fast user switching?
>
> Thanks,
>
> Lang
>[/color]