When attempting to reinstall System Center Virtual Machine Manager 2008 R2 (SCVMM) the installation fails with the following error:
Library Share MSSCVMMLibrary already exists. Specify a unique library share name, and then try the operation again. ID: 819
This can occur if there is a mismatch in the local path field in the SCVMM database for the corresponding library (i.e. the path of the Library seen in the database is different from the actual path of the Library).