Update won't proceed: "could not open key"

When trying to install the newest update I receive the following message:

could not open key:
Unknown\Installer\products\02E4201EB4F21DD41920AB739DA1136C\SourceList\Media. Verify that you have sufficient access to that key, or contact your support personnel

Ran regedit, searched for 02E4201EB4F21DD41920AB739DA1136C and gave every entry full control, to no avail: the issue remains.

Deactivated the key, re-ran the installation, turned off my AV (Norton Internet Security), still no go.

What can I do? Please help.

Many thanks in advance.

Try to download the latest version from this link: http://www.emclient.com/dist/v3.5.118…

And make sure you have admin right for your user account.

Sorry for the delay, I was travelling.

First of all, thanks for answering.

Still get the same message and yes, I have admin rights…

Here’s the screenshot: