How to Clean Install but then retrieve & restore my Keychain and Mailboxes.

Question

For months now, there have been a large number of irritating problems with my system - and I'm not enough of a techie to resolve them.
It is as though my machine is stuck in the past.
Spotlight doesn't index well - and fails to find up to two thirds of my files - including most of the newer ones.
Dashboard remains at the point at which I upgraded my disk drive. I know this, because a clip from Safari (a web-page with drives for sale) comes up - laboriously slowly - every time I open dashboard; when I delete the clip, it simply reappears the next time I open dashboard after a reboot. Similarly, post-it-style notes made in the Stickies app just vanish after a reboot.
When I open TextEdit, the same untitled file I was working on back in the early summer opens with it; I close it, it's back again the next time I open TextEdit. Alterations I make to Text substitution disappear the moment I close the panel.
All new bookmark additions to Safari vanish from my bookmarks when I restart Safari.
Every time I open iTunes, it thinks I am opening it for the first time. I can't tell you how many times I have agreed to their Software License.
My iCal alarms go off ad infinitum even when I turn them off and for months after the event in question.
And so on, and so on. It's like living with an Alzheimer's patient who keeps asking you what day it is.
I have twice reinstalled Snow Leopard (and rebooted my way through all those software updates) to no avail. My system - or at any rate my applications - still think it's early summer 2010 and any changes since then are forgotten; and Spotlight continues to be virtually useless.
It seems intuitive that some of these problems might be associated with individual preference files and caches for the various applications. But, even if I knew how to correct such problems, I'm concerned it might take me days - even weeks - of messing around but without solving all of my problems.
I have to say, I am tired of having half a Macintosh at my disposal. And I'm inclined to do something drastic.
The obvious solution to these pernickety system problems is completely to reinstall Snow Leopard (onto an erased hard drive) and start from scratch. What has stopped me doing this so far is the fact that, together with the various keycodes that came with my applications, I would also lose all my e-mails and accounts from the Mail application - and all the various passwords in my Keychain.
Surely there must be some way to retrieve just these select items alone from backup after a clean install? (And - yes, techies - I KNOW that Apple doesn't offer a "clean install" these days but you know what I mean: I want to reset everything; then retrieve a few select items - but WITHOUT the complete migration - which would likely, in the process, reinstate all those corrupted preference files or permissions or whatever it is that is messing around with my machine's short term memory.)
So here's my question again:
How - following a "clean install" - do I locate and retrieve the specific ingredients that will restore my mailboxes and keychain to their current state, whilst leaving everything else "clean"?
Message edited by: Eric M Colvin
Message was edited by: Eric M Colvin

Answer 1

An alternative proposal I'm going to make is to set up a new user account. It seems highly likely to me that all, or almost all of these issues are related to the account preference files in ~/Library. Certainly the iTunes issue, Safari, TextEdit, iCal etc. suggest that your account is having trouble with saving any changes to its preference files which would result in anything you tried to do being forgotten the moment the application was closed.
So for a start, make a new account, log in to it and do a couple of experiments - make some bookmarks in Safari, change some TextEdit options, open iTunes - then close and reopen them, or even restart the machine. If the changes are saved, then it's definitely an account problem and there is no need to reinstall Mac OS. Worst case scenario then would be you might need to move your documents and settings over to the new account; however it's also worth taking a couple of steps to see if the original account can be fixed. Try the above step and if it works; if so, go to /Users and right click your home folder, then 'Get Info'. Under the section dealing with permissions, ensure that your username has both read and write permissions, then use the cogwheel to apply this setting to all folders and files inside your home folder (you may need to use your password to unlock the padlock for this).
There are other things that can be attempted even before moving to a new user (or reinstalling if the new user test failed) so it's still worth checking back here in case other people suggest steps, it just depends how much time you want to invest.
As always, back up all your data before troubleshooting.