I used to play this game on my system just fine, with XP Pro. Then my hard drive went out. I bought a new, slightly larger hard drive and installed XP Media Center instead of Pro because other games I have play better on MC. But now Sims 3 won't install. It starts installing just fine, then get to The Sims 3\Caches\Sunset Valley.objectCache and just sits there and sits there and sits there. I'm not having a problem with any other game installing or playing. My system has twice the memory required, and like I said, I've played this game on this sister before. My new hard drive is 70GB larger than the old one was, but other than that and switching from Pro to Media Center nothing else has changed. The tech support folks at the official Sims 3 site have been no help at all. Any ideas?
Looks like it's my game disc, even though it looks okay to me. I've borrowed another disc and it's now happily installing, so it looks like I need a new disc. If it still ends up not installing I'll post another update, but for now it looks like it's just a disc issue.
Just an update: I used another disc to finish the install, and the game now plays fine with my disc (since I started the install with my disc, it's registered under my CD key). Apparently I have a bad spot in my disc, but it doesn't seem to affect actual gameplay. So try borrowing someone else's disc to finish the install before you buy another copy of the game.