Hi Ken and Rick,
Rick, I think permissions are right, since I didn't touch anything after using the auto-install facility of Plesk to install Moodle in /site2. Ken, as far as your question about domains is concerned, /site1 is the root directory for virtuellement-la.net, which works perfectly (but only when I used the auto-install facility of Plesk to install into / instead of /moodle). And the domain associated with /site2 is gurq.net. Yes, each of the sites uses a different DB and data directory, automatically created when I did the installs. Again, what's weird is that virtuellement-la.net, with the SSL certificate associated with it, works just fine. Just try it and see: https://virtuellement-la.net. Again, when I put a basic index.html in /site2 there's no problem getting to the home page of gurq.net. As I read more and more in the manual about Plesk 11 I see that there is what appears to be a sort of technical tug of war betwee settings in Plesk and settings via GoDaddy's own DNS zone interface. In fact, at one point I contacted GoDaddy and asked them which I should use to set, say, nameservers. The answer: "No, no, don't use Plesk; use our interface for this." This I found to be sort of a weird answer, since they are the ones who give me access to the Plesk 11 manual that says specifically to do this and most other things via Plesk. Anyway, thanks to both of you guys for trying to resolve this mystery. I'm sure it will be soon, and since I now have my Moodle site at virtuellement-la.net up and running as my mission-critical site, serving streaming video, I can turn my attention in a more relaxed manner to the gurq.net Moodle problem.