@agussol. Yeah, that is weird. I just tested it on IE9 and Chrome on Windows 7, and it works! I’ll have to install Firefox on Windows to test, but there are my screenshots so far:
So, I find it strange that yours was working initially, and now it is not working, but all my tests on your site are working. Maybe you can share some screenshots, so we can figure it out.
At the end of it though, as I mentioned before, I have no control over how Google Docs Viewer works, I can only offer access to the service.