Have you downloaded any camera mods? I find that some of them act strangely on my new computer. Gunmod's cameras worked perfectly when I had XP, but were a little odd with Vista. I downloaded some by Tom420, and they work much better for me. I do still use Gunmod's live camera, which seems a little more precise than Tom420's. (link -
http://www.modthesims.info/download.php?t=312294)
If you haven't downloaded any camera mods, you might benefit from trying them out. Just back up the original files, so you can go back to them if you need to.