If you're trying to open an Enterprise Vault log file from your own PC, eventvwr will warn you that it can't find information for the events:
The description for Event ID 3419 from source Enterprise Vault cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.
Fortunately, this can be easily solved. Just follow these quick steps:
regsvr32.exe "C:\Program Files (x86)\Enterprise Vault\VaultMessages.dll"