Weird "URL:Mal" popups with Firefox

Viruses and worms
1

In this evening when using Firefox Avast has popped up two notifications at the time telling that web shield has blocked a malicious website. This seems to happen every time soon after I open firefox. I’ve done nothing else but watched Youtube and using few other offical websites sites I know for sure aren’t dangerous. Here’s the info what Avast gives (sorry about the language, I have Finnish version as a default):

http://i.imgur.com/yAbFvqH.png

Second popups have the same information, minus the “:443./1.0/sync/1.5” part in URL bar. I’m yet to scan my computer to find if something is actually wrong, I just wondered if someone would be able to tell what those notifications are about.

2

Might be false positive…every time I open Yahoo’s home page this comes up.

3

Also see - https://forum.avast.com/index.php?topic=166531.0.

4

I am having the same thing happen to me today after bidding on ebay and getting a threat detected message. After doing a scan, a win32: malware-gen was found and successfully repaired. I did a boot scan as well that found nothing. Then when opening firefox, I got the URL:Mal message.