Suddenly node edits don't save in IE but do in Firefox

Boy this seems very strange. Suddenly edits to nodes would not save in IE6 and 7 but work in in Firefox. In IE, when clicking submit, it comes back to page view but changes are not made.

I believe I solved the problem my changing my database connection string from:

$db_url = 'mysql://username:password@localhost/databasename'

to

$db_url = 'mysqli://username:password@localhost/databasename'

(e.g. 'mysqli' instead of 'mysql')

Perhaps my web host did some kind of an upgrade.

But the thing that seems so strange to me is why this would work in Firefox but not IE, as what does browser have to do with that?

Curious if anyhow knows about this.