Wii U

ok, this is driving me nuts.
I transfered over 200 VC and wiiware games from my Wii to my Wii U.
of course I have to download that huge mass of games now as the transfer only transfers the download-log.
My problem: Sometimes the download(Mario collecting coins) interrupts with some error-code and asks you to try again. well, I had the same on the wii sometimes and i had no problem to "try again". Now on Wii U it seems that this event seems to completly freeze(it gets stuck at a black screen) the console. Power button doesn't work on console and pad. The only solution is to unplug the console and wait 15 sec.

This happened 4 times now and I'm afraid that the unpluging will damage the console in some way.