So, I did the repair. I haven't used WLM enough since then to know if I'll get the "unknown error" message again, but the following problems still remain unresolved:
1) Duplicate "contacts" listings when trying to forward an email (there is no pattern to this)
2) "Sent" messages being sent to "drafts" (I deleted everything from "drafts" after the repair was done, so maybe this got fixed?)
3) "Sent" items folder always indicates that I have sent two emails. When I open the folder, there are hundreds. Is this a time-controlled default?
None of this is earth-shattering, just annoying. I can work around any of it. Who says one has to understand
annoying things (or people), anyway?
OK, just got the "unknown error" message when I tried to delete an email. ??? I guess that make four unresolved items.