Fans switching on yesterday saw the console's calendar reset to January 1, 2000, locking them out of games and wiping away saved high scores.
The problem affects the older-style "fat" console - but appears to have hit all 23 million boxes around the world.
The flaw is thought to have occurred when the machines' clocks tried to tick over to March 1, 2010.
They were disconnected from the online gaming system PlayStation Network at midnight on Sunday.
The network is used by owners around the world to challenge each other to multiplayer games via the net.
But many furious fans have flooded messageboards to say they are unable to play off-line.
Many have lost hard-won "rewards and trophies" built up on hit titles such as Call of Duty.
Some owners have even reported calendars returning to 1999. Stuart Miles, editor of gaming website Pocket-Lint.com said: "This is to gamers what the Toyota's faulty accelerator pedal was to drivers. If you want to play games on a console, and can't, what good is it?"
A Sony spokesman said: "We've identified this problem as a bug in the clock functionality. We hope to resolve it within 24 hours."
The error is a big embarrassment for Sony, who have just launched a major UK TV campaign for their latest game title Heavy Rain.
