I just got this message when switching on my wii, I switched it off then back on again and it seems to be working fine, has anyone else had this message and is it anything to worry about, I should also point out I have no homebrew/hack stuff on my wii at all, also ever since the last update it seems to freeze far more frequently than usual, also the browser seems to crash more frequently, there are times when I have to unplug the wii since it wont shut down, and I don't remember ever having to do this until recently.

I had that problem with my old wii. It worked fine for about a week or two after, but then it wouldn't turn on so we sent it to Nintendo and they said it was beyond repair and they couldn't retain our save files. So, back up all the save files you can onto an sd card as quick as possible just to be safe. Hopefully this doesn't happen to you, but it's better to be safe than sorry with something you've probably put a lot of time into.

I got the message as well. When I opened my SD card it said all my files were corrupted,so I just restarted the system and every thing has been fine since. It seems like it may be a one-time thing

When I saw it I thought that was my console wiped, but everything is working fine and all my files seem to be ok, both SD and system memory, I have a second smaller SD card that I might just use to back up some of my save data from time to time, at least from my most played games anyway, I remember I got a similar message with my Dreamcast once and that resulted in a whole VMU being wiped completely.

Just remember that most games with wifi data can't be copied over, like SSBB and mariokart.

I had this happen once I think in the first few months of owning a Wii. I did a hard reset (powered off at the front panel) and have never seen it since.

I had this same thing happen 2 days after Firmware 4.0 while booting the disc channel with RB2. Hard reset just like Sean, have never had this issue since. Didn't lose a thing.

This is happening to me right now.

Every time I load the Wii after not playing for about a day, I get a "system corrupted" message and I have to turn the system off manually (the system button).
But then once I power it on again, it goes away.

But I've had my Wii since launch, and it didn't start doing this until less than a few monthes ago. o.0
Anyone know why it's doing this?

I've seen this happen once, and no, I cannot offer a clue as to why this would happen, sorry!

I'm in the same boat. First startup of each day that message pops up, resetting the Wii allows me to move on. Nintendo said that a format is necessary, but since I can't back up Brawl or Animal Crossing, I'll just have to restart the Wii each time after I see it.

Never happened before 4.0.