This has been mentioned plenty of times on these forums!
Once you install any of the Sims 2 Expansion then the previous games appear to not work. This is not true!
The expansions add extra content to the original Sims 2 game. So you actually start the game from the last installed expansions desktop shortcut.
All your Sims 2 game is still there but now you start it from a new desktop shortcut.
