For some reason, when I try to update the virus database, I get “Downloaded update is corrupted, try again” message at the end of the download. This has been happening since June 20, 2013. I have the kernel.shmmax=128000000 in my sysctl.conf file so, no worries there.
It seems I had a similar problem 3 years ago and it was related to using Privoxy, which I’m not using now. I have Linux Mint 15.