This issue could be caused by an infection is removed while there are still references to the infected files in the system. You could find a model example in this blog article, for example. Restoring the system to a certain point could have restored the infected file too. (In such case, it is likely that another anti-virus software installed will remove the infection and the same situation may occur again.)
The abovementioned obsolete issue caused by AVG cannot be root cause of this problem, even though the error message is exactly the same.
Please let us know your findings.