Tested in Opera and Firefox latest versions, worked fine. IE is no longer supported on Omnimaga, but it should work. I don't know about Chrome.
Does it work now? If not, then it might require you to clear all your browsing history or something. I know I have issues with cached MP3 files, for example. Sadly, I can do nothing since this seems like a problem on your end...
EDIT:
Mozilla Firefox 4.0.1: Works fine, both when logged in or as guest.
Opera 11.11: Works fine, both when logged in or as guest
Internet Explorer 9: Works fine, both when logged in or as guest
Chrome 12.0.742.91: Works fine, both when logged in or as guest