After applying a number of successful New Zealand Daylight savings hot fixes we came across one that brought down an entire SharePoint farm. The patch seemed to install ok but the SharePoint products and technologies wizard threw an error around step 9.
Bascially the issue was that it left all the content databases in an inconsistent state. This left us in a very dangerous situation as it is not possible to uninstall the hotfix.
The Event Viewer showed an error that suggested the version of SharePoint recorded in the Content DB was 3.0.149.0 but that it was expected to be 3.0.150.0.
To get things going again I updated the value in each content database and did an iisreset. This operation would of course be completely unsupported by Microsoft.
The basic message here is to apply the hotfix with caution as things can go horribly wrong.
Recommendations:
If possible perform after hours or plan an outage period
Backup all related SQL databases
Quiesce the farm before applying
Install the operating system daylight savings patchs prior to upgrade
Log in as a Farm Administrator before running the hotfix and SharePoint Products and Technologies Wizard (Very important as this may affect DB access)
Resources
Note that you do not have to install the SPTimer job hotfix (kb938663) if you install the SharePoint/WSS daylight savings hotfix (kb941422).