You may have an old version of your browser supporting less code than more recent versions. You might consider using Opera 9.0+, Mozilla Firefox 2.0+, or Netscape 9.0, though this browser is not being developeded any more. It has now been superceded by Mozilla Firefox and Opera in taking on Internet Explorer, after the 'browser wars' at the end of the 1990's.
If you must use Internet Explorer, It should be version 7. This should be set to allow blocked content. However I.E.7 is still incompatible with some of the latest W3C specifications, which other browsers meet. (See Site Management page for more information.)
All these browsers are freeware and can be downloaded from the internet. If you don't know how to do this, leave well alone.