The problem is like I suspected, the 'value' attribute isn't being sent by IE nor Opera.
For the email form I simply put in a hidden input with the same name "actn" and the value "submit" - so when the form gets submitted, "actn" always has the value "submit"
For the shopping cart I can't do this as easily because when that gets submitted it has to support various values for all the functionality I have in there. I will have to try to put in a hidden input element on the fly at the time of the submit, if I can. Hmmm... Will have to go through the source carefully again.