Disable Citrix workspace control (in Ps4.5 and web interface)

Hi,

can you please help in disabling totally the workspace control in Citrix presentation server? In other words, the application does not have to follow an user that logs to another computer with the same user account?

What I did already, but unsuccesfully:
- access management console / select the web site of the web interface / workspace control disabled (cleared the "Enable workspace control" tick).
- in manage session preferences, cleared the "Web interface should override the Ica client name"
- set "ClientName=" in "\Inetpub\wwwroot\Citrix\Metaframe\conf\default.ica" (and the other *.ica files).

.. but no way. Still a user logs on to the web interface, executes an application - then moves to another Pc, logs in again and executes the application again and the application follows him :(( . This is undesired in my scenario where several colleagues log in with a common user name and steal the application each other :-(( ... you may guess their disappointment.

Versioning:
- server with MsWindows2003, Citrix presentation server 4.5 with hotfix rollpack 1, web interface 4.6
- Ica clients v. >= 8 in WindowsXP

Thank you very much in advance for your kind support!
Best regards.
Diego.