The Tivoli Monitoring 5.1.2 Ressource Model "Logical Disk" checks in the cycle time always the Floppy Disk (A:) on Windows.
The ITM queries are performed to Windows CIM classes and those classes return data on ALL logical disks (inlcuded floppy disk).
Resolving the problem
Unlikely there is no workaround from IBM Tivoli Monitoring point of view. This is a Microsoft issue.