Q: Missing "VeriSign Universal Root Certification Authority" - How was it deleted?

I am helping out a friend who cannot connect to various websites over SSL because Chrome and Safari report a certificate error.

Example:

https://onba.zkb.ch/

Certificate chain should be:

• VeriSign Universal Root Certification Authority
  • Symantec Class 3 Extended Validation SHA256 SSL CA
    • onba.zkb.ch

However on this friend's system, the certificate "VeriSign Universal Root Certification Authority" is not found by these browsers (however Firefox works fine).

I can probably "fix" by installing a new copy of the cert, but am first wondering what happened to the old one!?

The user was apparently able to connect to onba.zkb.ch without certificate issues until about 1 month ago.

Any ideas how this was deleted?