modmii modmii modmii...
...
ModMii!!!!
lol, only cuz you said not to I couldn't resist
But seriously, it sounds like you have an outdated IOS55 (IIRC that's the IOS used by the latest internet channel) or outdated internet channel itself (or both).
You could use modmii to download WADs that are definitely working, or you can continue blindly installing whatever internet channel WADs you find on the net (not a smart move btw). If you don't want to use modmii for whatever reason, use nus downloader to download\pack WADs for the latest version of IOS55 and the internet channel for your region, then install them, and the problem should go away.
I have to ask these questions because you seem to have something against ModMii.
-do you have bootmii installed?
-do you have a nand backup?
-do you have priiloader installed?
If the answer to any of these questions is "no", then you followed a shit guide to softmodding your Wii, and you should seriously consider resoftmodding your Wii from scratch using a proper softmod guide, like ModMii. ModMii will not only take care of all the items listed above, but it can also help you update your IOSs, cIOSs, Wii Channels (like the internet channel), themes, usb-loaders, etc.