I Have Windows XP with SP1 and no other antivirus software ! Only Spyware Terminator but they worked 1 year together without any problems.
Doesn't Spyware Terminator have a start-up protection function ?
There are a number of anti-spyware programs that stop new entries being added to the startup of msconfig. This will kill the ashDisp.exe avast icon, check that this isn't happening with ST, it may be advisable to disable ST, reboot and reinstall avast.
The ashDisp.exe isn't part of the avast security but an interface to settings, etc.
As a temporary measure until this is resolved you can create a desktop shortcut for this file C:\Program Files\Alwil Software\Avast4\ashDisp.exe (the avast icon and interface to the providers). Right click on the file and select Send To, Desktop (create shortcut). You will need to run this after each boot until the problem is resolved.
Check the option in the Appearance tab of Program Settings. Or Make a link to ashdisp.exe in your startup folder.