Ok, I've read through the forums, and while there are several reports of freezing, nothing was quite 100% with mine. So if anyone has any insight before I send this away to nintendo, here's what I got.
The Wii U console freezes, making a loud buzzing noise through the TV speaker for about 5 seconds, during gameplay. The only way to continue using the console is to shut it down by pressing the button for 4 seconds or by unplugging it.
First occured while swapping figures in Skylanders SWAP Force, and most often occurs during this process. Can occur during normal gameplay as well. No consistent level or play time.
Mario Kart 8 crashes in this manner during races. No consistent time point or race.
Mass Efffect 3 crashes in this way, usually during explosions. Not consistent.
Crashes in Wii mode as well. Notably during battles in Okami, preceeded by shadow/graphics glitches. In Wii mode, however, it will not respond to the button on the front and requires unplugging.
These crashes occur while online and when no network connection is present.
I only have one downloaded game (Pikmin 3), and have not observed the crash in the game, but I have not played it since the crashes developed.
The system is only a couple of months old (it's the Mario Kart 8 bundle). I utilized all of these games successfully for about a month before the issue appeared in Skylanders SWAP Force, and they seem to be getting more common. To me, it looks like a memory issue since it seems to occur mostly when the system is under heavy load. The fan is not obstructed, is running normally, and does not appear clogged, and the system does not seem hot when these occur (though I have no idea if the design of the Wii U would allow you to feel the heat without disassembling the unit).
Any ideas or troubleshooting I might have missed is welcome.
Thanks all.