Hey guys, I found out the problem. Hopefully this will fix your freezing problem.
I remember someone on the forum saying that in Animal Crossing, Wii Speak doesn't work. Guess what, a USB keyboard doesn't work either. In fact ANY OTHER USB device doesn't work... like a USB LAN Adapter.
If you're using a USB LAN Adapter to connect online you need to switch to a wireless connection (unplugging your USB LAN Adapter doesn't work; if you don't have a wireless connection then you need to delete your wired connection settings). WiiConnect24 (not sure it matter if you have it on or off) will try to connect online 1 minute into gameplay. Since the only thing that's active is a USB flashdrive/HDD WiiConnect24 will "unmount" your flashdrive/HDD and will try to use it to connect online (yes it's stupid lol). This what cause the freezing.
Also, this affect installing a game via Wii. I thought I couldn't install a game because my disc driver is "old and worn out" (I bought my Wii January 2007 and it's a DMS drive; have Wiikey v1 installed) but now I can install both retails and backups with no problem (including games like SSBB). I guess WiiConnect24 will try to connect online no matter what you're doing but it only affect the USB Loader.
Actually, it only affect apps that use cIOS rev9. I have trouble using Wad Manager 1.3 after I install cIOS rev9 and notice the app use cIOS if found. I thought a wad couldn't install because there's something wrong with it (it freeze 1 minute into installing!) but after switching to a wireless connection I try installing the same wad with no problem.
So that's my finding. Guess we now know what's causing it (hopefully).