1. Jave Plugin Problem
If you're using a trusted site like YouTube or a special site for your work or school, you might feel safe enough to enable a vulnerable plugin in order to view the site’s content.
If the Java plugin still cannot be displayed properly, you can click "Java" program from the start memu(windows), select "Configure Java", and then click "Security", and switch "Security level" to "Medium". In this case, everything supported by Java will be displayed. (Also try http://community.spiceworks.com/how_to/show/65737-java-error-missing-required-permissions-manifest-attribute-in-main-jar )