Sounds like a time zone issue to me:
Time zones and Daylight Saving Time (DST) are sometimes confusing. If you travel between time zones, do you set your clock forward or back? If a friend sends you an e-mail at noon, whose time zone is reflected in Microsoft Outlook—yours or your friend’s? What day should you change your clock for daylight-saving time, and do you move forward or back an hour?
Fortunately, Microsoft Windows XP helps you answer these questions by automatically translating times from other computers into your local time zone. Windows XP can also automatically adjust your clock for DST. Traveling between time zones is easy because you can select the new time zone, and Windows XP sets your clock correctly.
Your computer keeps track of time using Greenwich Mean Time (GMT). Your computer automatically adjusts the time on your system clock, in incoming e-mail messages, in the Event Viewer administrative tool, and elsewhere to the correct time zone. It is important for you to set your time zone correctly and to update it when you travel. If your time zone isn’t kept up to date—even if your clock is set correctly on your computer—the time stamps on e-mail messages you send will be wrong.
For example, if you are in the Eastern United States time zone (GMT-5), and a friend in the Pacific United States time zone (GMT-8) sends you an e-mail at 8:00 A.M. (your friend’s time), Outlook converts the time to 11:00 A.M. to reflect your local time zone. Similarly, if you monitor events on remote computers in other time zones, Event Viewer always displays those event dates and times in your local time zone.
How to change the time zone
To change the time zone and enable automatic adjustment for DST
1.Right-click your system clock, and then click Adjust Date/Time.
The system clock right-click menu with Adjust Date/Time selected
2.Click the Time Zone tab. Click the list, and then click on your time zone.
The Time Zone tab with Central Time selected
3.Select the Automatically adjust clock for daylight saving changes check box, if your region uses daylight-saving time.
The Time Zone tab with “Automatically adjust clock for daylight saving changes” selected
The Time Zone tab with the OK button selected
Now, all references to time reflect your new time zone. This includes the times shown for incoming e-mail messages, event times in Event Viewer, and when scheduled tasks run.
Note: If you use Event Viewer, DST can cause unexpected behavior because Event Viewer changes the displayed time (and possibly the date) for events that have already occurred. For example, if an event occurred at 6:00 P.M. in standard time, after you move into DST, that event appears as if it had occurred at 7:00 P.M.