If you are an AVG user (7.5 or 8.0) you need to do an update right away. Yesterday an update that was released recognized a Windows XP system file (user.dll) as a virus and recommended deleting the file. If the file did get deleted you would not be able to boot up and have to do a restore. AVG has corrected the issue leading to the false positive and users should download the latest update.
This article may contain affiliate links. Click here for more details.