I was having problems with iframes in posts and pages. Initially, I could place the iframe in the code and the page or post would appear ok. But, I could not go back and edit the posts or pages, because the page content area would just go blank as the iframe tried to load in the page content editor. Temporary solution - go to users, and disable the WYSIWYG editor. I found a better solution that allows me to use WYSIWYG though...use Mozilla Firefox...get the add-on called Xinha...when you go to create or edit your posts/pages, just right click in the code/page content and start Xinha. It works like a charm and has alot more features than the default wordpress WYSIWYG editor. Hope this helps.