I would recommend that you perform a manual uninstall See this EA Support Page for how to do that. You should then be able to install the game properly. When you get to the set up dialog where you are asked to confirm where you want to install the game, I recommend doing it this way. Take careful note of the name of the folder in Program Files where the game installer want to install the game. Normally this would be: C:\Program Files\EA Games\The Sims 2\ Make sure you keep the sense of that when you choose the Browse button and make the new folder: D:\Games\EA Games\The Sims 2\ The any future expansion packs can be added to the D:\Games\EA Games\ folder in the same way. It's not important, but tidiness and consistency in naming is helpful in troubleshooting problems if they occur.
Hmm, I've got a good feeling it's either background processes or the CD or the CD drive. I don't think it's BP's however as I got along fine without them last time it was playable. When I inserted the CD, as it spun it made a sort of stutter sound before spinning normally. also when I try to stop processes in task manager, it says it could lose data or make the system unstable. Help? :S