Maxtherabbit , yes UAC was turned off. I tried it on all settings, but the installer still complained that it had administrator rights .
Imi, I didn't have another account (I'm the only person who uses this machine), so I unlocked the guest account, but when I did as you said, the installer just refused to run. So I reset the PC (which now had the guest acccount), logged into the guest account, ran the installer and it worked! Except near the end of the download it complained about a C++ program not being present and seemed to lock up (no change at all for well over ten minutes). I should say that the PC has been running fine for everything else for a good while now, so there's no problems that I'm aware of with anything other than this program, and the firewall and virus killer aren't interfering with the program at all.
Anyway, I stopped the running (but seemingly stalled) installer, deleted the installation, re-ran the installer, and everything downloaded fine. Then I ran it, and no matter what I do, I just get a black screen with the menu sounds playing. According to the game's forum, there is an as yet unidentified problem with some graphics drivers and this latest version of the game. I tried manually editing the games video settings, and even downloading the game in full administrator mode (which I didn't think would fix it, but you try everything since Windows can confound logic) but the black screen problem persists. I'm not dying to play it, so I'll wait a few days and then follow whatever suggestions have been posted in the game's forum in the meantime, or hopefully they'll have patched the game to fix the bug.
Every version of the game up until now has just been a simple run-the-installer-then-when-it's-downloaded-and-installed-you-just-start-and-play-it experience, I don't know why the administrator rights problem has emerged with this version of the game.
I was going to end this post by saying that it had been that sort of a day (and it had), but of course, for most of the planet, it's been that sort of a year. If only the worst problem in the world was video games not working right.
Thanks for the replies and the help, it's much appreciated.
