I had a problem with Comodo Firewall version 5.0.163652.1142
The message I was receiving from both the status/tray icon and Summary page was
"Comodo Firewall is not working properly!"At this point it needs saying that I think Comodo is a great product and I appreciate its presence as a free and purchasable product. It received high marks from reviews and my own experience. I wouldn't have tried so hard to fix the problem I was having with it, if I didn't think it capable

After noticing the icon which consisted of an exclamation point inside of a triangle on the Comodo shield icon I searched the installed help file to see what this meant, but couldn't find the answer. Then, I went to the forums. The relevant post I read suggested using an INF file to install a network service under the repair folder in the Comodo installation. The repair folder didn't include such a file.
(To be accurate the fix was posted a couple years ago, but it was the only hit I could find. It was discussing version 3 and the tech said with version 4 it would be fixed. I had upgraded from version 3 and then had this problem.)
At this point I uninstalled version 5 and reinstalled it.
For 3/10ths of a second this worked. But less than a second later the icon reappeared during the boot process. So then I uninstalled it and put version 3 back on, which had been working fine before the upgrade. (The upgrade from version 3 to later version was done by clicking the check for upgrade button, so I don't know if that install routine uninstalled the previous version or just upgraded, but all subsequent installs were preceded by an uninstall) But the problem with version 5 was now effecting the installation of version 3, also.
Long story short I did a lot of uninstalls and reinstalls and reading to see if anyone had recently experienced the same, but nothing worked.
Finally it hit me (glory to God!) that I had seen when things worked, under the device manager tree, some low level drivers for Comodo. I was able to locate them again, and there was no initial indication that they were broken (there was no tell-tale exclamation point in a yellow circle that windows often puts for misbehaving devices) Upon clicking it there was an error code which I have forgotten, but believe it was 10.
I deleted all three Comodo drivers which I would have thought would be removed upon uninstalling the app, but was not.
At this point, after reinstalling version 5.0.163652.1142, things are working perfectly once more.
I write this in hopes that anyone else who has experienced this and if it is not covered elsewhere--might find this helpful.
One must have device manager open and then select Show hidden devices under the View menu to see the Non-Plug and Play devices. The Comodo Internet Security Firewall Driver which goes by the service name Inspect was the important one, I believe. There's also a Helper driver and a Sandbox driver, the latter of which was not put back with the latest reinstall.