[問題] My phpBB appears "Critical Error"

[lawrance]

I haven't touched the system files, but one day when user login, it shows the following error message:
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phpBB : Critical Error

Could not get theme data for themes_id [7]
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I have no idea what it is or how to solve it. Anyone can help?

[Mac]

err... have you read: http://phpbb-tw.net/phpbb/viewtopic.php?t=15329

Give us those details

~Mac