Am 08.06.2018 um 17:51 schrieb dl2uv:
My Latitude E4300 laptop worked flawless until the KB4100403 was due for
installation. The installation was performed and a reboot was forced.
When booting, the laptop shows a litte blue circle, which can be moved
with the mouse. This condition lasts forever. The windows-10 functional
update 1803 is installed since May 2nd.

Any hints?

Klaus
Thanks's for all your help.
Deinstalliung the anti-virus software (avira) and performing a clean
boot did the job.
KB4100403 was installed without any problems.
Klaus