Extremely unlikely malware will rename a target disk in a TC.
But TM is known to get itself in a knot on a fairly regular basis.. especially if you upgraded to Lion or firmware updated to 7.6.
Simple select the disk as it is offered or redo the setup of TM.
Look at the Pondini knowledge base of what goes wrong and how to fix it.
What happens if you just reboot the TC?
There are some real bugs in the latest firmware.. and lots of issues popping up.