@ Lukor
There are now an increasing number of post in the forums about this and the outpostfirewal.com forums also have a number of topics related to this and have even made one sticky as it must be cropping up.
http://outpostfirewall.com/forum/showthread.php?t=22529 Suggesting that they fix the problem doesn't unfortunately seem to do much, have both companies even spoken on this. It doesn't seem that Agnitum have as they have only come up with the disable the aswTdi driver, to the detriment of avast users.
Does the aswTdi driver not have any impact on the web shield ?
e.g. if disabled would this also disable the web shield ?
@ Spulci
If as suggested by lukor, uninstalling the Network Shield doesn't work with the compatibility issue in OP 2008 (they may just find the presence of avast and just throw up the compatibility window), manually editing the registry will require temp disabling avasts self-protection.
avast 4.8 has a self-protection built in and that may be what is stopping you making the modification, It can be switched off, Program Settings, Troubleshooting, check the 'Disable avast! self-defence module' and click OK before trying to do any mods.
I haven't a clue why Agnitum have done this there is talk that they thing the web shield is a firewall which is rubbish. What I can't understand is why other firewalls are quite happy with the aswTdi driver (Comodo, Online Armor, Zone Alarm, PC Tools), but Outpost can't.
I have a life subscription for Outpost Pro and this issue is one of the things that stop me upgrading to OP Pro 2008.
I don't know if Agnitum have contacted Alwil about this (I'm just an avast user) to explain why they feel this warrants the disabling of of the aswTdi driver.