Hi Jay
We've been doing some investigation and found that in some unusual cases, some centres which use networks like RM CC3 do not always have GeoTrust, the SSL certificate authority installed by default. As ASDANonline uses GeoTrust Global this will prevent the eAssessment software from connecting. In order to check this, open Internet Explorer and go to Tools, Options, Content tab, Certificates button, Trusted Root Certificates tab. You should see GeoTrust Global CA listed as shown below.
http://img690.imageshack.us/img690/336/geotrust.th.png
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If you do not have GeoTrust installed, you can download it from http://www.geotrust.com/resources/root_certificates/certificates/GeoTrust_Global_CA.cer
You can install this on each individual PC however you may want to add the certificate to your Group Policy so that it is available to all computers your network. Please see the following technet article for instructions Add a trusted root certification authority to a Group Policy object: Security Configuration Editor
Also, depending on how restrictive your IE settings are, you may need to add https://www.asdanonline.org.uk to your list of trusted sites in Internet Explorer.