Today is the day when Microsoft releases patches for its many different products, and it looks like there is an issue with one patch, KB 3001652, as many users are reporting that it is locking up their machines while trying to install.
The patch, you can view all the details here, is a rollup update for Visual Studio 2010 Tools for Office Runtime.
Microsoft appears to be reacting quickly to the news as it looks like the patch has already been pulled after there were a significant number of users reporting the freezing issue, as we no longer see it on our machines when we run Windows Update.
This is not the first time Microsoft has had issues with patches; back in August of 2014, the company had to pull a patch as it was causing machines to BSOD, and following that event, Microsoft had to pull another patch in September that impacted OneDrive for Business.
While this issue is not as severe as the issue from August, if your machine did freeze while trying to install the patch, your only option is to perform a hard reboot that could result in lost work if you did not save before running the update. Thankfully, it does not appear that this patch caused any blue screens but locking up while installing a patch is never a good thing.
[Update] That patch is back in Windows Update and should be safe to install.