IE9: JS and Java errors when open document and discard changes

When opening and closing documents using the right mouse click I get the following error:

SCRIPT5007: Unable to set value of the property 'HippoDestroyID': object is null or undefined
hippoajax-min.js?w:lm=1352700222, line 1 character 1491

I also get in the CMS the following error:

An error has occurred, sorry for that.

java.lang.NullPointerException: null
Failed to instantiate plugin class 'org.hippoecm.frontend.editor.plugins.field.PropertyFieldPlugin' for wicket id 'home.cluster.cms-static.plugin.servicesLoader.cluster.cms-services.plugin.hippostdEditorFactory.cluster.cms-compare.plugin.viewerPlugin.cluster.default.left.item' in plugin 'home.cluster.cms-static.plugin.servicesLoader.cluster.cms-services.plugin.hippostdEditorFactory.cluster.cms-compare.plugin.viewerPlugin.cluster.default.plugin.body' (JcrPluginConfig:/hippo:namespaces/hippogogreen/comment/editor:templates/default/body)

An error has occurred, sorry for that.

java.lang.NullPointerException: null
Failed to instantiate plugin class 'org.hippoecm.frontend.editor.plugins.field.NodeFieldPlugin' for wicket id 'home.cluster.cms-static.plugin.servicesLoader.cluster.cms-services.plugin.hippostdEditorFactory.cluster.cms-compare.plugin.viewerPlugin.cluster.default.left.item' in plugin 'home.cluster.cms-static.plugin.servicesLoader.cluster.cms-services.plugin.hippostdEditorFactory.cluster.cms-compare.plugin.viewerPlugin.cluster.default.plugin.documentlink' (JcrPluginConfig:/hippo:namespaces/hippogogreen/comment/editor:templates/default/documentlink)

see screenshot.

This might have been caused by Out-of-memory on the server (256 MB)