I ask that you read the following carefully. First I will explain what I’ve been doing recently, what websites I went to that seem the most relevant and then ask my actual question. I want to be thorough.
I recently began using Google Chrome in a sandbox when I surf the web. The sandbox program I use is called Sandboxie. Not to insult anyone’s intelligence, but if you didn’t know, a sandbox is a separated area on your hard disk where you can run programs, and any malware or viruses from using those programs are basically contained inside of the sandbox and cannot make permanent changes to your computer. When you delete the contents of the sandbox, any malware or virus files during that session, contained in the sandbox, are supposed to be deleted. Sandbox programs are used for testing new software that may be malicious and for browsing the web more safely. I will admit, freely, that I used the sandboxed Chrome today to browse porn videos at this website: xnxx.com. Yes, I admitted that, but I thought it was important to mention for obvious reasons, as porn websites are notorious for viruses. Again, when I did this, I was using a sandboxed Google Chrome. Again, please read everything carefully to ensure you don’t overlook anything. 
Now, moving on. I have an account with www.imvu.com. For those who don’t know, IMVU is a virtual 3D chatting client where you use an avatar to instant message other people, basically a virtual chatting universe. While in sandboxed Google Chrome, I tried to go to www.imvu.com. This address does not usually give you a secure, encrypted connection. In other words, there is no https before the address. However, when I typed in www.imvu.com, I was getting re-directed to a website which read something like this (do NOT actually try going here): https://secure.imvu.com/landing/next. This page looked as if someone had rigged it to look like the actual imvu.com page. I got very suspicious. So, I called my sister on Skype and had her try to go to imvu.com on her computer, and when she went to www.imvu.com, she reached the actual homepage with the proper background. The page she reached was very different from the one I reached, and it seemed obvious that I was on a fake site. This was all contained in a sandboxed Google Chrome. I ran a Malwarebytes scan hours ago, before any of this, as well as one after this, and both came back clean.
However, I have noticed something strange. After terminating the sandboxed Google Chrome and deleting the contents, I went to www.imvu.com again, on another sandboxed Google Chrome, and this time I reached the actual IMVU page. After a while of being on the actual site, maybe a couple of minutes, however, I received this notification from Avast!. The image is below (on tinypic.com):
http://tinypic.com/view.php?pic=6yjpdc&s=8#.VfljsN9Viko
Just in case the link doesn’t work, the Avast! notification read exactly as follows:
Avast Web Shield has blocked access to this page because the following certificate has been revoked: *.lijit.com
I received this notification from Avast! while I was on the actual IMVU website. I also received this same notification once earlier, but I can’t remember what website I was on the first time it appeared. This all happened while browsing in a sandboxed Google Chrome. What is this notification and should I worry about it? I have seen it twice, so that’s a bit disturbing. Both times I received this notification, I was never actually “on” this website (*.lijit.com). What is this notification all about and what should I do about it? I do not even know what lijit.com is and certainly have never tried to intentionally access this website!