Exactly the problem...in a terminal server environment, you normally don't want users to interact with the anti-virus software interface. They have limited (AD user) rights for a reason and any actions required by the avast! software should be handled by the system administrator, not an uninformed user. Additionally, the aswDisp.exe process consumes memory for every users logged into the terminal server.
Does anyone else run avast! on a Citrix/terminal server (win2k3) with recommendations for this issue?