I am glad to see this post. I was beginning to believe it was something that my daughter did accidentally. She also received what looked to be a legitimate AVG update box that appeared on her screen. She is set to receive auto updates and thought that is what this was. She is not too savvy about watching how updates arrive, which is part of the problem.
Within a short time, her laptop locked up. Fortunately she does a regular backup. Her geek friend was able to clean up the viruses and trojans (over 500) and she was good to go.
This occurred about a month ago. She was using the free AVG version. I went to the AVG forum and opened a new thread, but at that time, no one had heard anything about this. I haven't been back to check it since.
A caution to AVG users - you may want to turn off auto updates or at least be sure they are legit before downloading.
Received what appeared to be a legitimate, regular AVG update notice. Started to download update when my daughter advised that she had heard this update was causing problems on other people's system. Stopped download in mid-process....had to do a full system restore to get the gremlins out. 3 hours of my life that I'll never get back. Nice.