The issue may occur if the "TZ" entry in the computer's Environment Variables was incorrectly configured. This entry is often used to override the default time zone.

To resolve the issue, modify the TZ entry with the correct value:

1. On the computer that did not scan correctly, right-click My Computer and select Properties.
2. Click the Advanced tab.
3. Click Enviroment Variables.
4. Under System variables section, look for the "TZ" entry.
5. Correct the value or delete the TZ entry. To correct the value, check your time zone. You can use third-party applications like Time Zone Converter. Examples of TZ valuse are "America/New_York" for Eastern Time, "America/Chicago" for Central, or "Europe/London" for Britain (UK).
6. Restart the computer.

In other instances, the issue may be caused by a bug in Windows Vista, Server 2003, or Windows XP. To identify if the issue is applicable to you, refer to Microsoft's article FIX: Windows-based applications that use the TZ environment variable may not work as expected because of changes to DST.