The question is, How did the virus get on the machine?

It was "protected" by Norton 360, which includes Norton Antivirus. This was kept up to date and the drives scanned on a regular basis.

However...this year we're moving to Trend Micro. I've been thinking about it for some time and the report in "Consumer Reports" convinced me. This has just reinforced it.

If, on the other hand, I were to find whoever wrote the virus, I would have to shake his hand...and his head...and his spine...and his kneecaps...with a baseball bat. One of the old-fashioned wooden ones.