I created a form in Acrobat 9.0 professional, saved it with "Extended Features in Adobe Reader" and saved it.
I sent it to a few coworker's to test. It works fine on one machine, they can enter data in the fields and "Submit" the recipient gets the pdf. On the other coworker's machine after they enter data and hit submit, it says "Operation failed".
Both machines have the latest version of Reader and are running Windows XP.
Not sure, maybe if you can share the form, I can have a look at it.