SYSTEM_DRV (Z:) - Appeared one day then it was gone

Has anyone else over this past weekend noticed if you went into your file folder, under "This PC", had noticed a new partitioned drive called SYSTEM-DRV Z: (or what ever letter it was assigned) when in fact, no one created a new partitioned drive, then when you rebooted, it was gone?

I was wondering why I saw it, I knew I never made any changes to my drive, I couldn't access it even though I am the administrator, couldn't even check its properties. I then Googled it, saw others had the same thing occur, just that day (Saturday afternoon on December 3), most of whom are Lenovo users, including myself. This drive was only 227 MB in size, and that was all the information I was able to get out of it.

I scanned the PC with ad-aware and Norton's - nothing showed up, so then I rebooted and it wasn't there since...
Very odd, wondering if anyone had the same changes occur to them.

When Windows installs it installs a small Hidden System Reserved partition in the front of the drive with no drive letter.
Some program might have added a drive letter to this partition and then Windows removed it on reboot.
Go to Start/Search and type diskmgmt.msc, right click the diskmgmt results and Run As Administrator. In the Elevated Disk Management window in the lower pane, you can see all the drives, and see the hidden System Drive.