The "Find Groups" popup which you can launch from the "Edit Global Permissions" page breaks in IE:

–
Line: 1
Char: 2
Error: Invalid argument.
Code: 0
–

This is due to the "strWindowName" parameter having a blank string:

window.open('/spaces/opengrouppicker.action?key=&startIndex=0&actionName=dosearchgroups.action&existingGroups=&onPopupSubmit=setgroupsToAddTextField',
'Entities Picker',
'status=yes,resizable=yes,top=100,left=200,width=580,height=550,scrollbars=yes'
);

See: http://developer.mozilla.org/en/docs/DOM:window.open