Windows NT 3.51 Does Not Have Updated Daylight Saving Time

• Microsoft Windows NT Workstation version 3.51
• Microsoft Windows NT Server version 3.51

SYMPTOMS

Many European countries have changed the date on which they switch from daylight savings time to standard time; it was the last Sunday in September and is now the last Sunday in October. Windows NT 3.51 is currently configured to switch in September.

RESOLUTION

Follow these instructions to manually change from daylight saving time:

WARNING: Using the Registry Editor incorrectly can cause serious, system- wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of the Registry Editor can be solved. Use this tool at your own risk.

1. Locate the time zone used in the registry:



1. Start Regedt32.exe.



2. In the HKEY_LOCAL_MACHINE subtree find the subkey:
   
   SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones



3. In the list of time zones locate the one you are using by finding the one that the value "Display" that matches the setting in Control Panel/Date/Time.



2. Modify the Time Zone Information:



1. Open the value TZI in your time zone key to get into the binary editor.



2. You should see binary information like this:
   
   C4FFFFFF00000000C4FFFFFF000009000000050003000000000000000000030000000500020 0000000000000
   
   The values "C4FFFFFF" are dependent on the offset from Greenwich time, so you may see different values than those shown above.



3. On the first line, move the cursor to the vertical line between c and 10. Change the character "9" right next to it to the character "A".



4. Click OK.



3. To make the change effective, start the Date/Time tool in Control Panel, change to a different time zone, click OK, and change back to your original time zone.



4. Verify that the change worked by examining the following registry value:
   
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneinformation StandardStart = REG_BINARY 00000A00050003000000000000000000
   
   It is important that the third byte is an A.

MORE INFORMATION

Below is a script for the Windows NT Resource Kit tool REGINI, which can help you automate this process. You have to customize the key name and values for your installation. Please note that the bytes in the REGINI script are ordered differently than showed by registry editor. After running the script you need to either go through step 3 above or reboot the computer.

This sample is for the English version of Windows NT 3.51 running in the following time zone:

(GMT+01:00) Berlin, Stockholm, Rome, Bern, Brussels, Vienna

 \Registry\Machine
   Software
      Microsoft
         Windows NT
            CurrentVersion
               Time Zones
                  W. Europe Standard Time
                     TZI = REG_BINARY 0x2c

0xFFFFFFC4                       0x00000000
0xFFFFFFC4                       0x000A0000
0x00050000                       0x00000003
0x00000000                       0x00030000
0x00050000                       0x00000002
0x00000000

 \Registry\Machine
   SYSTEM
      CurrentControlSet
         Control
            TimeZoneinformation
               StandardStart = REG_BINARY 0x10

0x000A0000                       0x00030005
0x00000000                       0x00000000 

Additional query words: prodnt

Keywords : ntregistry ntreskit NTSrvWkst
Version : winnt:3.51
Platform : winnt
Issue type :