date() output 23 hours behind

Using a UNIX timestamp for "June 26, 2007, 12:00:00 AM" I compared the output of two calls to the date() function. One on a Windows server running PHP 5.2.1 and another on a Linux server running 5.0.5. The output on the Linux server is 23 hours behind the output of the Windows server, showing "June 25, 2007, 1:00:00 AM".

The code is identical. Only the PHP and Apache version and the operating system vary. Time zone is not a factor as this is a pregenerated integer value for a future date.

What could be causing this discrepancy?

is it possible one of the setups isn't configured properly for daylight-savings?

is it possible one of the setups isn't configured properly for daylight-savings?

Wouldn't that mean it would only be wrong by a single hour, not 23 hours?

the US daylight-savings changed from its normal pattern this year though I believe, and computers that haven't been updated will be calculating incorrectly.