Windows 7: Unmapped Drive Letter Shows Up

As can be seen in the screenshots below, a weird drive letter shows up under "Computer" which however is not mapped in the Disk Manager. I guess it is some kind of service that creates this drive. How can I find out, which service or program is responsible for it? How can I remove it?

Pictures:

Solution 1:

It might be related to Office Click-and-Run. This Microsoft KB article has more information:

Why do I have a "Q:" drive when I use Office Starter To-Go?

Office Starter To-Go uses the Office Click-to-Run technology that must use a virtual application drive. This virtual application drive is why you have the Q: drive.