Hanging installation and loss of previously installed Expansion Packs

[Milhouse Trixibelle Saltfucker III]

So, remember that friend who I tried to convince to come here? Well, they were recently installing new expansion packs (mine, actually - we performed an exchange) and decided to reinstall from the beginning and then go through in order, but apparently, at first, the Pets installation froze, and after restarting the computer, they turned on the game but the OFB expansion pack was mysteriously missing. I advised an uninstall/reinstall, but now all the expansion packs are freezing during installation, and none of them work. I'm trying to help but I'm really at a loss. What should I say now?

Edit: I should also mention that it hangs at the very end, when it says "Please wait...", apparently. I'm pretty sure it's when the game does it's whole "checking to make sure previous expansions are up to date" deal, but I can't be certain, since I haven't seen this happening. I personally suspect registry corruption.

[Kazzandra]

I personally suspect registry corruption.

That sounds correct to me.Do you know how to manually delete the registry keys before reinstalling?

[Milhouse Trixibelle Saltfucker III]

I do, yes, and I've had my friend working on it this whole time. I just wanted to make sure it wasn't something different.