OK, my 2p worth:
As far as order goes, whilst I have never used Comodo firewall I would still advise having avast installed first.

I have applied that for my Outpost Firewall Pro (or suite) as it detects avast as being installed and offers compatibility mode to disable its web control and anti-spyware modules, etc.

If avast is installed first, there would be less chance of any possible interference from comodo/defence+ during the avast installation. So I would suggest that order of installation and see if it makes any difference.

I would suggest that a clean install of avast (as you used to have avast5 on here previously, but I can’t see anywhere where you say what version of avast you have) to ensure there is a clean start point:

  • Download the latest version of avast, 6.0.1203 and save it to your HDD, somewhere you can find it again (if you didn’t save your last download) before starting your uninstall/clean install of avast and comodo. Use that when you reinstall.

  • Download the avast! Uninstall Utility, aswClear.exe find it here and save it to your HDD (it has uninstall tools for both 5.x and 6.0.x).

    1. Now uninstall avast! (using add remove programs, if you can’t do that start from the next step), reboot.- 2. run the avast! Uninstall Utility from safe mode, first for 5.x if previously installed and then for 6.0, once complete reboot into normal mode.- 3. install the latest version, reboot.