How to deal with clients

My wife is in hospital. I'm the “spouse of the patient, from Hell”. What this means is that I ask too many questions. Between each visit, I use Google, all university accessible Scientific Journal databases, etc., to find out more about how little we know [me and the medics] about what's going on.
Yesterday, I realised some of the Medical Magic... It's actually the same in Tech Magic.
DON'T TELL THE CLIENT
So, what does this mean? Well, it's pretty simple. As a professional, as data unravels, one hypothesises. While doing this, it may not be such a good idea to tell the Client about all possibilities. Just tell them:
“Don't worry, we'll have this sorted by the end of the week”
or
“We're all going to die, so there's nothing to worry about”
Uh, Oh, don't tell them the latter. It's probably to radical... Let's try
“Your hard disk it totally corrupted. They're quite cheap these days. Let's get a new one, re-install everything, and load your backup”
Uh, Oh....
Anyhow, what dawned on me was that as professionals, we all do the same. The more we know, and hypothesise, the less we should tell the Client while we're trying to make our minds up what the hell we're going to do next.
As a patient, I don't like this. I'd like to know it ALL. On the other hand, if we accept this, the implications are that I don't need to worry about things:
My Accountant: should worry about my tax returns.
My Bank Manager: should worry about how to keep me supplied with cash.
etc...
That's a happy thought ;-)