The fault appears to cause the machines to stop booting or get stuck in a failure to apply the new settings.The error message is 0xC0000034. If you get it, please pass on the info to the NOC/ IT Admins as quickly as possible so they can make changes to the WSUS server on site to limit the effects.
The fix for the time being is to apply the full service pack to machines and not the WSUS deployment of SP1.
Please be aware there are issues with editing the pending.xml file as discussed in the second link, so please read both before performing a repair.
Info on the issue and repairs;
The issue with editing pending.xml
Will always look for more info on this, email me on mcglynn.joe (at)gmail.com