I also had a Windows Update yesterday and mine was fine. It was "Update for Windows 7 for x64 based systems, (KB24541014)". Was yours the same? You can check by going to Start > Control Panel, then open Windows Updates, then "View update history".
I checked that Knowledge Based at http://support.microsoft.com/kb/2541014 and all I see is Hibernation does not work or memory dump file is not created after you install Windows 7 and Windows Server 2008 R2 Service Pack 1. So, it doesn't appear to be a 'system changing' update that would cause problems.
Tell us more.
1] Did you have any other issues with this computer? If so, what were they?
2] What happens when you try to open these programs, like Adobe PDF Reader and Google Chrome? Any error messages?
3] What is the exact Rundll32.exe error message?
A simple solution would be to do a System Restore back to just before this update was installed. Windows 7 always creates a Restore Point before installing updates, so there should be a restore point available, (Start > All programs > Accessories > System Tools > System Restore).
Windows 7 downloaded an automatic update yesterday and now several of my programs will not run including Adobe document reader and Google Chrome. Help! I am now getting constant Rundll32.exe errors and I have no idea how to fix this situation.