If the secondary message is "Load initialization failure due to active applications", this error was likely caused by an attempt to load into a database that has one or more non-loader clients connected.
Before reattempting the load operation, the non-loader users should be instructed to disconnect, or the -u flag should be included in the Data Vault Loader invocation to disconnect other users routinely.
If the secondary message is anything else, then an internal error has occurred. Report this error and the circumstances to Informatica Global Customer Support.