I can't imagine it would be a problem that would require re-installing the game again. If it works under your account, and has issues on his account, I suspect that maybe something might be wrong with his account settings and/or EA Games folder.
I also suggest backing up his
entire EA Games folder. BUT, it may be sufficient to simply just save his
Downloads,
SavedSims, and
Neighborhoods folder. You may also want to back up Collections, Music, and Movies, if he has any customized content there. And also, possibly the Teleport folder. I would say those are the most critical folders to save.
Then... since you are using Windows XP, I suggest creating a new User. I assume you installed sims under an account that had Administrator rights. If that is the case, you also most likely installed it so that All users can run the Sims. So... I think it might be best to create an entirely new account.
Then, back up your son's C:/Documents and Settings/Your Son's Account folders.
In this case, I would say the critical folders would be:
Cookies, Desktop, Favorites, My Documents, Start Menu
Maybe Local Settings. You might not really need Cookies, because those can always be recreated.
However, in the backup you just created for the My Documents folder. I would DELETE the EA Games folder, since you should have a backup somewhere else already of the folders you should save (that I mentioned above).
After backing this up. I would copy all of this over to the new account
C:/Documents and Settings/Your Son's NEW ACCOUNT
Go into this new account, start up the Sims 2. Have it create all the necessary folders and what not. Exit the game.
Now, go to your backup of sims stuff, and copy those folders over into the appropriate places in
C:/Documents and Settings/Your Son's NEW ACCOUNT/My Documents/EA Games/The Sims 2/
Theoretically, by creating a new account entirely, I would think that it is basically starting with a fresh,
clean slate. Then, having the game create all the default stuff, the game should theoretically be clean. And finally, copying all the Sim data you backed up, your son wouldn't have to lose his game.
However, if you find that there is STILL a problem, after all of this, then I would highly suspect something may have been corrupted in your son's Sims 2 game data.
In which case, its fuct and he'd probably have to start from scratch.
[Edit: I forgot to mention, after you go through all this. You can delete the old account, and rename the new account to the previous name of the old one. Confusing? I hope not.
]
Ste