Update KB3000850 fails to install

Hi there,

I have a problem installing update KB3000850. It downloads and appears to install OK until the computer restarts to complete the installation. It gets to about 8% of configuring windows updates and then I get the following message:

failure configuring windows

undoing changes

The computer restarts and is usable. I don't know a great deal about windows error reporting but I checked the C:\Windows\Logs\CBS\CBS log and found the following message:

CBS Failed installing driver updates [HRESULT - 0x80070003 - ERROR_PATH_NOT_FOUND]

I checked the Event Viewer and found the following message in the Windows Logs\System section:

Event ID: 7023

Source: Service Control Manager

The Windows Modules Installer service terminated with the following error:

The system cannot find the path specified.

I have no idea which path it cannot find. I have tried running the SFC and DISM commands and have tried the Windows Update Automated Troubleshooter but none of these seem to fix it. I understand there is a problem with the Avast anti-virus software but I am running Norton 360. I am using Classic Shell and am not sure if that is causing the problem but don't want to uninstall it if the error is being caused by something else.

Any help or advice would be most gratefully received.

Thanks in advance,

Richard