I had a problem installing Java 8 update. Got two different messages: Error 1603 and Key not valid for use in specified state.
I had checked for malware and viruses beforehand and found nothing. I renamed User/Appdata/roaming/Microsoft/crypto/RSA to RSAcorrupt and tried installing again. It worked successfully. Dave Horton http://compgroups.net/comp.lang.python/ -- https://mail.python.org/mailman/listinfo/python-list
