I had to press ashDisp in C:/Program Files/Alwil/Avast for the Resident shield Icon to be displayed in the Tray. Is this normal, earlier it would automatically come up at startup
It's not normal... it should be there after logon. Are you using any security application that could be blocking the ashdisp.exe link to be automatically started? (like WinPatrol, TeaTimer, Spysweeper...).
Do you use any other antivirus in your computer?
Let me see on the next boot, if not is there a fix to this.
Which is your Windows? 98, Me, XP?
Can you try to repair your installation?
Go to Control Panel > Add/Remove programs > avast! antivirus > Remove. Then choose Repair function in the popup window (Repair). You must be connected to the internet while repairing.
If this does not help, can you uninstall / boot / install / boot again?