Yesterday afternoon I went through some digital gymnastics to get my main computer back online. It turns out that the process of backing up and restoring my data with Carbon Copy Cloner somehow rendered my login account dysfunctional. I could log in to the cloned data on my external drive, but when the [same] data was transferred to my main computer, I couldn’t log in. I found a Unix hack for tricking the Mac into thinking I had never walked through the process that creates my login profile, so that it would make a new user profile for me — but the process hung in the middle, so that I suspect I had hosed the whole deal.
Wiped the hard drive, re-cloned the back-up, then this time tracked down my original install disk, found the clever option for changing a user’s password, changed my password to what I thought it already was, and hey, presto! Back in business.
Booted the newly-restored computer, and started up my Mail application, which I had carefully avoided using, because I wanted my mail to download to my main computer, not to download mail to my school-issued computer. I had been using the online Gmail interface for the week my main was under repair;it was clunky and slow, I fell behind in my communication because I dislike using the web interface, but I had finally gotten everything sorted out.
Then I noticed that I had mistakenly booted the backed-up version of my data, and after a week of painstaking reservation I had just downloaded all my mail to the wrong computer.