Try Tools > Edit Users > Clear Locks
And see if it allows you to edit the database.
In which program will I find the Tools menu?
Keep in mind I am not running version 2.0.
In folder O:\Chassis\Elec\Mentor Graphics VeSys Library\ you will find a file called "H-D Diagram Library.loc", just delete this LOCK file.
Deleting the .loc file solved the problem.
For reference the .loc file is created every time the database is opened so if VeSys Components doesn't close down correctly the .loc file can be left. As you've discovered it is as simple as deleting the .loc file.