update 4/14/2015 - The GlobalSign certificate issues have been reported as resolved.
Update 4/10/2015: A problem discovered on 4/8/2015 with the GlobalSign certificate service protocol appears to be the root cause of “invalid issuer” errors displayed on sites that are using thew new SHA-256 trust chain. We believe this problem to be an issue with GlobalSign and they are currently investigating the issue. We do not currently have a timeline for when they will resolve the issue.
Due to some recent DNS issues with Apple that affected OSX and iOS it seems that Safari is having some issues receiving a list of known bad certificates, which can make Safari refuse to accept Virginia Tech signed SSL certs and may prevent Safari from loading those sites. A temporary workaround is to use a different browser such as Firefox or Chrome.