Anyone looking for possible virus database update problems, please see this post. It worked for me.
Good Luck!
…The Same Problem. Well, I was going to post in here: https://forums.comodo.com/antivirus-bugs/cant-update-virus-database-cis-3571735439-merged-threads-resolved-t29013.0.html
…but it says the bug is “Resolved”! There I read carefully and tried most of the solutions proposed, according to my system (including those which had to do with Registry). There were the intelligent questions of 2 users: TAUPING and PNOCANDO, BUT AS NO-ONE CARED FOR THEIR ENQUIRES… I come here for Help:
I’m having exactly the same problem as theirs, including the same computer environment: Win XP SP3 32bit, I use no other User Account, but this of Administrator, without a password, using no proxy (but a wireless connection, for it’s a LapTop), sec software besides Comodo, no: the Windows Firewall I disabled although I think I also have the malitious spyware remover…
Nonetheless I’m using the latest CIS version (.439), but still cannot get Comodo to update the Virus Database, nor the Program itself. Can anyone please help??
Welcome to the forum alxazazel 
The latest CIS version is 581 please download from here
https://forums.comodo.com/feedbackcommentsannouncementsnews-cis/comodo-internet-security-313126709581-released-t49566.0.html;msg355806#msg355806
Dennis
Why, thank you very much Dennis2! 
Previous to the actual installation of this newest CIS version I had to uninstall the program as I was prompted, and all my previous settings were lost 
[again CIS asking lots of enquires for program policies that I had already answered], in spite of this annoyance finally CIS Virus Signature Database got updated, at least that’s what it says: Version being 3528.
O0
Hi all,
Until today, I like many have had issues with installing Comodo Anti-Virus definitions. The symptoms I seen is that the updater would only download about 20% of the cav file, sometimes a bit more, which obviously if the whole file is not downloaded it could not successfully apply the update. The issue with this process that I noticed is not necessarily a problem with the Comodo app itself but something messing up with the combination of Windows Update and Comodo running together (at least in my case and particularly when I am not at home on slower networks).
The solution I have found that has worked for me is to:
[ol]- Open Windows Update from the start menu
- Click the change settings link from the left side menu bar
- Change the setting for Important updates to “Never check for updates (not recommended)” and click on OK
- Right click anywhere on the lower task bar that does not have an icon and click on “Start Task Manager”
- Once the Task Manager is open click on the processes tab
- Find the process for Windows Update in the list given (if you sort by image name it should be located toward the bottom of the list)
- Click on the process and press the “End Process” button
- At this point windows update should not be running in the background any longer and you can start the Comodo update like you normally do and wait for it to finish
- Once the virus definitions are updated you can reset the Windows Update settings back to the way you had them before
- If all goes well the virus definitions will now be updated and your system will be able update like it did before this process[/ol]
I know it is quite process to perform but seemed to be the only thing that worked for me.