blimey, i wrote that ages ago and i think option two was a complete coincidence that it fixed anything, i think really if it keeps happening you will have to get some dumps (through ADPlus or DebugDiag) as well as the client logs to see whats happening.
Previously Virtual Vault would lock up out look because a thread was terminated incorrectly and other threads waiting on it would just hang, doubt thats the problem but thats the kind of thing to look out for
I'd suggest download debug diag and have it monitor Outlook.exe for a hang or wait until it hangs and then generate the dump, if you then open up the generated dump you might see something where debugdiag tells you what the process may be waiting on, or at least what its doing
Once you have a dump and a full client trace, suggest opening a case with support
as for Outlvbs.dll, this is an Outlook issue so you might be able to find something on google, you could also run a Procmon and filter on Outlvbs.dll and see where Outlook is attempting to load it from
https://www.linkedin.com/in/alex-allen-turl-07370146
