Sony’s PlayStation Network (PSN) went into meltdown this weekend, logging users out of the service and preventing them from playing online games. That alone would be inconvenient, but users, including our own Brian X. Chen, are reporting that previously downloaded games — including Heavy Rain — cannot be played offline, and that trophies won in games have disappeared from the console.

Sony is aware of the problem, posting updates on both its PS3 blog and Twitter stream. Oddly, the issue is confined to the original big PS3s: The PS3 Slim remains unaffected by the problem.

Although Sony says it will have a fix by this morning, it has not yet said what went wrong. Anecdotal evidence points to a combination of DRM and firmware issues rather than a network outage. Affected units have their system date set to Dec. 31, 1999 (something impossible to do manually, according to PS3 News) or Jan. 1, 2000, and the consoles are only able to play non-protected games.

This, combined with errors such as the following:

8001050F - Hardware failure. Cannot update Firmware or connect to Internet

make us think that a firmware bug screwed up the date and/or connectivity, and the games’ DRM is thrown into a panic as a result. If this is true, it’s embarrassing for Sony. The other possibility is that the trophy syncing itself is breaking the games: games try to sync trophy info and refuse to work when they can’t. Non-trophy-based titles such as Metal Gear Solid 4 are unaffected.