Despite everything indicating that the 1.2 beta installation file is a *.tgz file, what is actually downloaded is *.gz.
I tried decompressing this via cpanel but it doesn't work. It just leaves a moodle-1.2-beta file with no extension.
I also tried the gzip and tar commands via a shell interface and they didn't work either.
This happened a few days ago, and I resorted to the *.zip version and that worked fine. I'll try that again.
But I'm curious whether I have done something wrong with the *.tgz (actually*.gz?) version, or whether there is a problem somewhere at the other end. This never happened to me until recent days.
EDIT: I've solved this problem. I simply changed the filename extension to *.tgz and it worked. Should have tried that a long time ago!