Recently a hard drive named OS (X: ) (space inserted so it isn't posted as a smiley face) appeared in my computer. It seems to be identical in memory to my actual hard drive, but is actually empty. What exactly should be done about this?
I think you may have a dynamic disk http://technet.microsoft.com/en-gb/library/cc737048(v=ws.10).aspx rather than a normal one. This might mean that you have two drive mappings to the same actual volume. This might or might not be an error - it might simply mean that the space on the real volume will be dynamically shared between the two mapped drives you see.
If your computer is less than three years old, you probably have a GPT disc partition structure, and if in addition you have done some uninformed meddling with some system-level software older than three years, this might be an unintended consequence.
However, I don't really know what I am talking about, and certainly until you know definitively what is going on, you must not use any partition manager to delete drive X:
I think it might be safe to copy a test file from drive C: to drive X: and see what happens. Or save a document to drive X: and see if it also shows up on drive C: root.