I really don't like Vista (I was just too lazy to reformat the drive on my brand spanking new machine) but I've never experienced any kind of those weird behaviours.
I installed the basegame, pets, seasons and BV. Only when I started sims the 1st time, Vista told me that Sims 2 is not compatible and sent me to EA to d/l an upgrade patch.
So now all what's left is the annoyance to move all downloads (because all the good programs like RoboMaid, Cleaninstaller, Download Organizer etc. install/work on the Files in the Admin account/EA Folders.
And since I refuse to run any game as admin, no CC shows up until I copy/move the stuff into my accounts Download folder
(Still being lazy I use a directory Sync program for that...of course resulting in having all CC 2x on my computer, which is no big deal on a 500 GB Harddrive and works as a convenient backup

Not that this is very helpful for you...but I suspect some kind of messagebox popping up which is covered by the Game's screen. and of course the comp waits for any input before continuing its work (otherwise you most certainly would get a crash/no response - Screen.
Try to run the game in a window for once, so you would see any popup boxes.
-le