If you wait for a long time, the emergency update will eventually complete (or fail).

If you hit Ctrl-Alt-Del and then select Task Manager, you’ll see that the emergency updater is running.

I have been doing some research on this problem, here’s what I’ve found so far.

To better understand the situation, take a look at the log for Comodo Firewall Events.
Change the date range to “Entire Period” and set an application filter for “Avast\Setup”.
In particular, look at the “Action” column.
This will show if the firewall is tripping up on the Avast Emergency Update.
If the action is Ask or Block, then the firewall is blocking access, which makes the update take longer (and it should eventually timeout and fail).

(If the action is Allow, you have weak rules and maybe you don’t really need Comodo? :wink:

Since the emergency update generates a unique filename each time, there’s no way to create an Firewall Application rule.
(There is no way in Comodo to create a rule saying “allow any application in the specified directory”, and for security reasons you wouldn’t really want that.)

I am currently experimenting with a global outgoing rule for an IP address range.
I don’t know how well this will work, and even if it does, it looks like Avast uses at least several address range, so this may be slow discovery process.

Another approach, which I am also experimenting with, is to disable or change the Windows scheduled task that launches the Avast Emergency Updater. If you go to the Windows Task Scheduler, you’ll see the task for the updater. You can try changing this (for example, removing the “At log on of any user” trigger). I don’t know yet if Avast will notice and reset the task.

Avast’s settings for automatic/manual updates don’t seem to apply to the Emergency Updater, and I haven’t yet found anything in their control panel that allows this to be turned off. Presuming that the updater provides a valuable service, an alternative would be to run the updater only when the user is already signed on, and that would avoid the black screen. The updater will occasionally run while signed on (you’ll see this when you look at the task scheduler), it’s the “At log on of any user” trigger that can cause the problem.

Hope this helps…