The problem has been discussed on the board before, but in summary:

When you connect a drive to a share this uses a connection. When you connect to the share using UNC this creates another seperate connection.

The solution is to either always use the drive ("H:\") to access the share, or to always use the UNC path to access the share, but not both.

Look for the clipart path in the application's own settings pages. You may find that if you set an explicit path it creates/populates a registry key. The application probably has a default value for the path if it has not been explicitly set, which is why you are having trouble finding a registry entry.