Just wanted to post here and inform of you all that the 2005 Holiday edition of the Official Playstation disc WILL nuke your memory card if you play it:http://www.consolegold.com/News/news.php?NewsID=583
Do you have the official Playstation Underground Demo Disk for Holiday 2004? If so, remove your memory card(s) from the console before playing Viewtiful Joe 2, or else you WILL regret it. From the Gaming-Age forums:
Everything was fine until I played the Jak 3 and VJ 2 demos on the Playstation Underground demo disk... The next time I booted up my system I went to the console to check something out and it told me that my memory card (1st party Sony) needed to be formatted.
Great. So, the demo disk erased my memory card. It was just fine before I put it in because I checked it to see something and afterwards I checked it again to see if it put any saves on my card. That's when it told me I had to reformat. I am going to try to recreate the conditions again just to verify but just a warning to be careful.
Update: I have been able to recreate this bug 100% of the time. It happens when you boot into the VJ2 demo and make it to at least the 2nd load point (where you get the mach FX).
According to posters, this is affecting any and all memory cards you may have inserted, no matter who made the card.