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“There is no magic fairy dust protecting Macs" – Dai Zovi, author of “The Mac Hacker’s Handbook"

WA Daylight Savings changes and how it will affect computers.

November 29th 2006 in Uncategorized

Microsoft have released a tool for the Western Australian Daylight Savings changes that affected home users should install:

But, what about the corporate environment?  As many of you know, I am based in Western Australia and have had to deal with these changes – yay for the politicians who did not look any further than the kitchen clock and their bedside table alarm when deciding to introduce daylight savings in Western Australia with only a few weeks notice.

For me, the easiest way to add a daylight savings ability to all computers on my network is to push out a registry script via my login script.  My networks run SBS2003, so all I had to do was create a registry file, and save it to the NETLOGON folder.

The registry file is as follows – if you wish to use this, only copy and paste the text which is in bold font – IMPORTANT NOTE: THE FILE HAS BEEN TESTED ON WINDOWS XP ONLY!  Registry Editor V5.00 files cannot be used on older versions of Windows.


Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\W. Australia Standard Time]
“Display”=”(GMT+08:00) Perth 2006”
“Dlt”=”W. Australia Daylight Time”
“Std”=”W. Australia Standard Time”


I then add the following to my login script:

REM Add a daylight savings zone for Perth to all systems
regedit -s DaylightSavingsPerth.reg

The registry change automatically enables the tick box to adjust system clocks for daylight savings if the user has local admin rights.

Note: I’ve used the same procedure on my home network – when users are NOT local admin, the registry file was imported, and the daylight savings option created, but it was not be enabled – this is because the local user does not have sufficient rights to change the time and date settings (an error message will be seen if the user tries to adjust date and time). 

Also, the registry file did not work for me on Windows Vista when I tried to apply it via the SBS log-in script – it worked  when run manually BUT I did have to manually adjust the current time because I applied the registry file *after* daylight savings had started.

I used the MSI on my SBS2003 server – the daylight option was created, but again was not enabled.

There is a problem with the daylight savings changes – all pre-existing appointments in Outlook that are during the first daylight savings period will move forward one hour – these appointments must be manually changed to their correct time.

IMPORTANT NOTE:  If you have recurring appointments that span non-daylight savings and daylight savings periods, you must adjust each appointment during the daylight savings period INDIVIDUALLY – do not open the series.

The calendar appointment changes don’t occur until after a reboot and even then may not be changed when you first open Outlook – they’ll morph a couple of minutes later.

The moving appointment syndrome only affects appointments from 3 December 2006 to 24 March 2007 inclusive.  It seems the registry file activates a daylight savings feature *for this year only* which means we will have to go through all of this again when a later registry edit is released.

All appointments outside of daylight savings periods seem to be ok.

Only two problems have occurred so far on my computer.

1. When I rebooted after applying the registry patch all managed applications were removed, and I was prompted to set up my Windows Automatic Update preferences.

 Reboot – managed applications were reinstalled – AU prompt gone
 Reboot – managed applications removed again – AU setup prompt back
 Reboot – managed applications installed – AU prompt gone
 Reboot – managed applications stayed installed
 Reboot – managed application still stayed installed.

2. My custom multiple home pages disappeared in IE7 (probably related to 1. above – somehow or other systems on my network spontaneously lose GPO settings on reboot)

Such spontaneous removal of managed software is a regularly recurring problem, most often happening after security patches or other software changes and seems to be related to Kerberos issues.  It’s a pain in the tush, to put it mildly, but people are getting used to it now – I just tell them to reboot and all their software will come back.

It is possible to stop the problem of managed applications spontaneously uninstalling when they fall out of scope – you need to edit the deployment options for the GPO to disable automatic removal.  Of course, this means that if you remove a PC from an Office OU that the software will not be automatically uninstalled, but we can live with that.

Further information for network administrators about daylight savings:

Exchange – OWA and CDO objects, both of which we use – nothing released yet – info here:

Sharepoint – nothing released yet – info here:


I have one last observation regarding the following quote taken from the microsoft.com artice:

“Outlook users need to apply the update for their Windows operating system. Following the update, existing calendar items which occur during the daylight saving period will appear to be shifted one hour earlier. Further information is available at http://www.microsoft.com/australia/technet/timezone/Outlook.aspx.” – my appointments shifted an HOUR LATER – perhaps this will have changed when I log in on Monday when the time zone changes have taken effect.

3 comments to...
“WA Daylight Savings changes and how it will affect computers.”


One hour later is right. A particular UTC start time in an appointment will resolve to something like 9am AWDT instead of 8am AWST.


Thanks HEAPS for this. The MSI would not work on my VISTA install or my MCE install on another PC(crashed out half way through.) However your Reg key worked perfectly on VISTA and I’m sure it will also work on my MCE PC when I get home tonight 🙂
Appreciate it.


A link does not open in Internet Explorer 6 on a computer that is running Windows XP Service Pack 2 or Windows Server 2003 Service Pack 1http://support.microsoft.com/default.aspx?scid=kb;en-us;926134
This issue is a result of automatic download blocking, a feature whereby downloads that are hosted on a Web site are not opened automatically.
If a Web site you […]

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