Backup Exec Remote agent for windows will not install on citrix server and fails with the Error 1603 in the install log
you can switch to install mode while lusers are on the server. However I would recommend that you disable log on for new users till you installed the stuff:
Please use the following command before you start with the remote agent installation.
change logon /disable
change user /install
change user /execute
change logon /enable
Please let me know if you have any other resolutions for the same.