I have the same version (Microsoft Calendar Control 10.0" is written in Components dialog in VB).
Probably control is not registered properly on your system or is corrupted (as say VFP). Try to find control on Office, Windows or VFP installation disks, copy them to your system and then register it.
Some other causes can be problems with Windows, Office and/or VFP. Get latest SP for all these and make sure they are installed properly.