The laptop is up and running again. After three weeks of no progress, I finally trekked up to the Apple Store in Cambridge and talked to their tech people there. Yes, it was probably a conflict in the Finder preferences that prevented the Finder from launching. Yes, it is entirely likely that the problem was caused by the CD Verizon gave me to start up DSL. (Besides, Macs running OS X do not need any additional software to access DSL, so the CD was totally unnecessary.) The simple solution was to re-install the operating system, archiving all the old preferences.
Carol is cat-sitting in Cambridge again. This evening while Carol was visiting Ann Taylor Loft in Harvard Square, I sat down with Mina the cat and the laptop. While the new operating system installed itself, I got out Mina’s favorite toy — a long springy wire with a handle on one end, and a little chewable thing at the other end. I held the handle and twitched the wire while the cat stalked the little chewable thing. She is a pleasant little black cat with a sweet face, but when she is stalking, her face is the picture of feline killer concentration. She would catch the little chewable thing, bat it around until it was “dead”, chew on it for a minute, and then get up and eat a couple of kibbles from her dish. (I thought the bit about eating the kibbles was a nice addition to the game.)
We played this very engaging game for most of the hour it took to re-install the operating system. After all the anguish I’ve gone through trying to fix the laptop’s problem, this was a particularly pleasant end to the story — playing cat games while the computer bascially fixed itself.