The title says it all really. I have been experiencing this in the problem, which I believe is still related to browsing HTTPS pages.
Browser Firefox 41.0.1, avast free 2016.11.1.2234 on XP Pro SP3.
I can be browsing quite happily and all of a sudden I can’t load HTTPS pages, I see this in these forums and other HTTPS sites.
I started by disabling HTTPS scanning, but at times that didn’t appear to work. Now I tend to just shut down the Web Shield (10 minutes option), but almost immediately enable it again. Now browsing those same pages is restored.
I agree that the HTTPS-scanning on XP is certainly not the cream of the crop.
I’ve it disabled since build 2225, after that no problems with the web shield, though.
I believe the Web Shield problems are possibly related to said HTTPS scanning, which I have left enabled and only stopping and restarting the web shield, quicker than disabling and enabling https scanning (as that would still require a stop/start cycle for the web shield to comply with the new settings.
Since this is a beta, I felt it important to test it in XP as they have changed the way that HTTPS scanning is achieved now. No inserting an avast certificate, but using the original cert. Whilst this basic explanation of mine is probably not exactly the way it is done, but I though it should be tested.
And the post is hopefully to draw attention to it and see if it is an XP related issue, in the same way it originally was when introduced (for XP SP3).