From: dynamic64 on
When trying to install the Windows Vista Update mentioned in KB943899, it
indicates it installs properly, but after I reboot, it says it failed with
Error Code E000023F. I can't find anything on MS, or anywhere else, that
indicates what the problem is. I've tried manually installing it, but that
doesn't work either. I've tried to do it in Safe Mode, but it won't install
in Safe Mode. It was working fine until this update.