If your certificate has expired or become corrupted, verify if this is the case by right clicking on C:\Program Files (x86)\InstallShield\VERSION\System\ISUIServices.dll to view the properties - if there is a Warning triangle this needs to be updated replaced.
The current certificate is VeriSign Class 3 Public Primary Certification Authority -G5
The certificate is no longer publicly downloadable from VeriSign Website, this particular site no longer exists, since they were aquired by Symantec.
In order to obtain an updated certificate for this
Name: VeriSign Class 3 Public PCA - Generation 5 (G5) Serial Number: 18 da d1 9e 26 7d e8 bb 4a 21 58 cd cc 6b 3b 4a Operational Period: Tue, November 08, 2006 to Wed, July 16, 2036 Certificate SHA1 Fingerprint: 4e b6 d5 78 49 9b 1c cf 5f 58 1e ad 56 be 3d 9b 67 44 a5 e5
Change the extension to cer, double click on the file to open the certificate, and click the install button. You should install this certificate to the Trusted Root Certificate Authorities Store.