What the hell is this!?

I got this error. I don’t have a clue as to what it is…

sun.security.validator.ValidatorException: PKIX path validation failed: java.security.cert.CertPathValidatorException: java.io.IOException: Response is unreliable: its validity interval is out-of-date
at sun.security.validator.PKIXValidator.doValidate(Unknown Source)
at sun.security.validator.PKIXValidator.doValidate(Unknown Source)
at sun.security.validator.PKIXValidator.engineValidate(Unknown Source)
at sun.security.validator.Validator.validate(Unknown Source)
at sun.security.validator.Validator.validate(Unknown Source)
at com.sun.deploy.security.TrustDecider.isAllPermissionGranted(Unknown Source)
at com.sun.javaws.security.AppPolicy.grantUnrestrictedAccess(Unknown Source)
at com.sun.javaws.LaunchDownload.checkSignedResourcesHelper(Unknown Source)
at com.sun.javaws.LaunchDownload.checkSignedResources(Unknown Source)
at com.sun.javaws.Launcher.prepareLaunchFile(Unknown Source)
at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
at com.sun.javaws.Launcher.launch(Unknown Source)
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.security.cert.CertPathValidatorException: java.io.IOException: Response is unreliable: its validity interval is out-of-date
at sun.security.provider.certpath.PKIXMasterCertPathValidator.validate(Unknown Source)
at sun.security.provider.certpath.PKIXCertPathValidator.doValidate(Unknown Source)
at sun.security.provider.certpath.PKIXCertPathValidator.engineValidate(Unknown Source)
at java.security.cert.CertPathValidator.validate(Unknown Source)
… 16 more
Caused by: java.io.IOException: Response is unreliable: its validity interval is out-of-date
at sun.security.provider.certpath.OCSPResponse$SingleResponse.(Unknown Source)
at sun.security.provider.certpath.OCSPResponse$SingleResponse.(Unknown Source)
at sun.security.provider.certpath.OCSPResponse.(Unknown Source)
at sun.security.provider.certpath.OCSPChecker.check(Unknown Source)
… 20 more

It looks like an expired SSL certificate.
In what context are you getting this? When connecting to a remote host?