The list of root certificates on your computer needs to be updated.

Missing Entrust 2048

DOWNLOADING THE ENTRUST CA (2048) ROOT CERTIFICATE FROM ENTRUST.NET

Please do the following steps:

1.)  Download https://www.entrust.com/root-certificates/entrust_2048_ca.cer
2.)  Double click on the downloaded root certificate and install it into the workstations root certificate store.
3.)  If the client is still installed on the workstation, reboot the workstation.  Once the certificate is properly installed, then the errors will go away.  If a single reboot doesn't remedy the problem, you may want to try another reboot.