ConwayLife.com

Whenever I close a particular file, I get the message "Could not save preferences file" or something like that. What does that mean?

It means Golly was unable to write to your GollyPrefs file. There are only two places where it attempts to do this -- when you hit OK in the Preferences dialog and when you quit Golly -- so I don't understand what you mean by "close a particular file".

Without knowing which platform you're using it's difficult to give an answer on why this is happening. Perhaps you've deleted the folder Golly uses to store GollyPrefs, or changed the folder's name or permissions. See the end of Help > Preferences for where Golly stores the GollyPrefs file.

I'd recommend upgrading to Golly 2.4 and see if the problem goes away. Or create an empty file called GollyPrefs (with no extension) in the same folder as the Golly app. You'll lose all your current prefs, but there's more chance Golly will be able to write to that file.

What I meant by "close a particular file" was closing one of two windows of Golly that was open.

Why would you have two Golly windows open? Parallel processing?

Opening up a file from a .zip extension.

If you open a downloaded file and it automatically opens a new window with an older version of golly, just copy and paste said file into your main golly window (which I would assume is 2.4.)