Hi Justin,
You can set the "Default Timezone Offset", the default timezone for new users & guests, in AdminCP->Settings->Date and Time Options->Default Time Zone Offset.
Warning: The following procedure will directly modify your database. BACK UP your DB before attempting. Very dangerous to do without a backup.
You can change the timezone for all current users via AdminCp->Maintenance->Execute SQL Query. Enter the query:
Code:
UPDATE [TABLE_PREFIX]user SET timezoneoffset = "[-12 through +12]"
Example:
Code:
UPDATE user SET timezoneoffset = "-12"
Doesn't directly answer your question... but it may help syncing things up.
-Nick, SEOvB Developer