Office starter 2010, home and office , home and business and started to go (which came preinstalled in many systems), use a form of application virtualisation (app-v/click 2 run). One of the side effects of this is that it creates a Q: which you have you have no access to.
Microsoft has a knowledge base article on click 2 run here and basically warns against hiding or storing anything in that drive - so you might want to, ideally just ignore the presense of the drive rather than trying to hide it.
This is an older question, but I rather doubt it has anything to do with the external drive in question.