No names given for the antivirus but here's a common issue. Many try those download accelerators and soon report your issue.
I have been having a problem with being able to download anything but photo's. I need to update my antivirus but cannot due to this. I either get the message "File is corrupt" or "Runtime error" or such and such has caused a "Fatal error" I am at my wits end with this and hope someone can help.