ghost.pif virus was rampant, at least in China, in May and June. Maybe it's "Made in China", such as Red Code is "Made in US". So the hard drive data is sent to Beijing website.
The chance is that the Chinese Contractor, if it exists, has virus infected, so when it is processing the HDs, the HDs got infected.

First of all, Windows sucks.
Second of all, some people is not professional when processing the HDs.