severity: minor thanks I guess it's really due to much less virii being transmitted to my machine. What the upgrade to Lenny has to do with that, I do not know. I have to investigate. The error message appears if there has not been transmitted any (recognized) virus in the last 24 hours. I presume it would also happen to the weekly graph if there was no virus detected in a period of 7 days, although I have not had that yet ;)