Consistent CIS update errors

Hi, I was running CIS 3.xx but a few months ago updates started failing every time - after downloading over 10Mb it would just die with an error. So I uninstalled and did a fresh install and now I am running 4.0.141842.828, but the same problem persists. Every time it downloads about 13Mb of 88 Mb (why on earth are these updates so huge?) and then dies with an error - the latest attempt showed error 0x80004005. Then it always says to check my internet connection. But my connection is fine, and continues to work fine after the error. This has gone on for a couple of months now, and I am still unable to update. I don’t want to do a fresh installation again, as the problem will probably just continue anyway.

I’m running CIS on Windows XP (2002) SP3, with 1Gb RAM and lots of free disk space. My net connection is fast enough, it doesn’t use proxies and I can access Comodo sites and any other site without problem. CIS diagnostics reports there is nothing wrong with my installation.

Any advice would be much appreciated!

Thanks.

Just me again…
Forgot to include that I’m not running any other background AV or firewall programs, and none have left any hidden traces in device manager either. At present I have AV database 5424 and have not been able to update since then.

Since posting this I found the related thread under Antivirus Help - CIS at https://forums.comodo.com/antivirus-help-cis/failed-to-update-the-virus-signature-database-t59099.0.html (I posted mine here instead because it seemed to have to do with all updates, program or otherwise, rather than just AV).
I tried some of the things in there with no benefit, and it seems like many people have this problem. Though they are trying to find something to fix in their own computer settings, I think the problem is at Comodo’s end - I never had any trouble whatsoever updating AVG when I had that, or in updating all the other software on my laptop - so it is not that my computer is blocking Comodo out, it is that Comodo is blocking my computer out for some reason.

Will monitor that other thread, but specific advice is also welcome on this one…

Thanks,
Kevin