Why doesn't my MS Outlook Web Access work on my PC?

I can't send an email using MS Outlook Web Access on my home PC. When I try to create a new mail message the new "untitled message" windows comes up. The To, CC, BCC and Subject fields are there, but the message field is missing. Where the message field should be is a frame with a little red cross in it. (Just like when an image isn't displayed on a website.)

I think I am missing the document control/object. What can I do to fix this?