iFrame disappearing

my client is having problems keeping his iFrame code to stay on the page. I have informed him that he shouldn’t switch between the VISUAL and TEXT editor of the pages, fearing it may gum everything up. But I watched him recreate the issue and it’s the weirdest thing I have ever seen.

He’ll paste in his iFrame code into the Content Editor is TEXT mode, click UPDATE and when the page refreshes, the code is gone!

I tried on my end, but could NOT recreate the problem.

I asked him about which browser he is using, and he is currently using Firefox, but he has seen this issue in Chrome, and he avoids IE like the plague.

I have disabled the visual editor when editing for him in his user profile, plus I have double checked that the “WordPress should correct invalidly nested XHTML automatically” is UNCHECKED.

I’m stumped. Anyone have any ideas on other settings I can check, or if I need to talk to the server admin about permissions.