Hi guys, I'm new here, but I had a similar problem.
Yesterday, I hacked my Wii U (black, 32 GB) with Tiramisu and Aroma and, until I get my HDD to install games, I installed three Homebrew apps with WUP Installer GX2: The Homebrew Launcher, WUP Installer GX2 and Nintendont.
And that's the error which I can't understand. First, I tried installing the three at the same time, and it started installing Nintendont but, when it was only 1%, the WUP Installer froze with a background beep. I turned off my Wii U and turned it on again. This time, I tried installing only The Homebrew Launcher, and it installed without freezing. Then, I tried installing only WUP Installer GX2, and it froze in the same way as Nintendont (at 1%), so I turned off the Wii U and turned it on again.
But that isn't the weird. The weird is that the three apps appeared installed, not only at the System Settings, but also at the Wii U Menu. I tried entering them one by one and all three worked perfectly.
I don't understand what happened. Does someone of you know?
By the way, I didn't mention that I installed the three apps to the NAND.