If you cannot view Oracle Enterprise Manager in IE, but can in other browsers, chances are you’ve hit the MS IE ssl keysize patch.
A patch does exist for this (the problem is due to OEM using a 512 bit cert) but if you like you can frontend EM with Apache.
Put this inside the ssl VirtualHost in ssl.conf (on Redhat / Centos) and restart apache.
# Fix 512 bit oracle EM Cert & IE
ProxyPass / https://your-localhost.com:1158/ connectiontimeout=5 timeout=30
ProxyPassReverse / https://your-localhost.com:1158/
then just go to EM with https://your-localhost.com