It must be interesting to work in a recycling plant, especially one that has mammoth companies like Microsoft providing some of the business. Some of the stuff that comes through is no doubt interesting, such as 70,000 copies of a certain office product. If you were given these perfectly good copies to recycle, would you think that you could get away with selling them on the black market?
It seems that some employees at Global Electronics Recycling did, or at least thought that it was worth the chance. It's not said when the incident went down, but Microsoft had given this enormous number of copies of Office 2010 to this plant to recycle, at which point employees sold them and reportedly made millions in the process.
For Microsoft, this incident involves two concerns. For starters, anyone who bought one of these copies of Office did not receive a legal version, and second, while this loss might not be substantial to Microsoft's revenue, it has to protect its trademark at all costs. The company could have technically let this go, but if it did, it could have faced losing battles in the future. If you have a trademark, you have no choice but to fight tooth and nail to protect it.
This isn't the first time Microsoft has had to sue a recycling plant, and it probably won't be the last. However, because of our shift away from disc media, the chances of this happening are going to be quite low.