One customer today reported several systems unresponsive after AVG detected "cryptbase.dll" as a malicious file. As far as we can see the file is fine and this is a false positive - but it stopped about 8 computers from working.
All of the systems needed a system restore and then an AVG update to later virus definitions. Two of the systems needed to be removed and re-added to the domain. The dodgy definitions appear to be timed at around 12:00 on Friday 24th November 2017.
Customers that pay for our RMM service can relax because we've already connected in to affected servers and forced your AVG Admin servers to perform program and definitions updates to ensure the problem does not present on your systems.