I believe this may well be an outpost issue.
What is the full text of the application error that you got ?
I am using Outpost Firewall Pro ver. 4.0.1025.7828 (700) which is a slightly later version. Now when I downloaded the latest version, I exported my configuration and uninstalled the old version before installing the latest OP pro version. During that installation it recognised avast and said that this could be conflicting application and did I want to exclude or avoid conflict (or words to that effect) I answered Yes.
Now in the C:\Program Files\Agnitum\Outpost Firewall (assumes you installed in the default folder) there is a file called wl_hook_data.cfg (this is just a text file), if you have this file add the following line to it:
C:\Program Files\Alwil Software\Avast4\ashserv.exe
If you don't have the file create it using notepad or any text editor and add the same line C:\Program Files\Alwil Software\Avast4\ashserv.exe (assuming you have installed avast in the default location). Save the file in the Outpost Firewall folder, the wl_hook.dll file should be in that folder so you should be able to see your new file is in the correct location.
Install avast, Reboot and hopefully you should be in business.
I have that same file and the ashserv.exe was already in the file. It was the only thing in there.
The full error is: "Ashserv.exe - application error
The instruction at "0x7c90efc0" referenced memory at "0x3e12d830". The memory could not be "read".
here's what it says in my event veiwer.
Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7034
Date: 9/14/2007
Time: 3:02:35 PM
User:
Computer:
Description:
The avast! iAVS4 Control Service service terminated unexpectedly. It has done this 1 time(s).
Event Type: Error
Event Source: Service Control Manager
Event Category: None
Event ID: 7022
Date: 9/14/2007
Time: 3:02:26 PM
User:
Computer:
Description:
The avast! Antivirus service hung on starting.
For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.
I don't know if that will help.
For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.