My client has reported two issues with two forms on her site. She says that customers have told her they've filled out the forms but their entries have not shown up in the form reports.

I checked the c5 and server error logs and found nothing to do with the forms. I cannot replicate the problems, the forms always work for me.

Some users claimed they hit submit and nothing happens. I have the forms set to forward to another page after submission. At the top of that page it says in big letters "Thank you for Registering!"

Another user filled out a form 4 times thinking it hadn't been submitted, but we did get all 4 of those reports.

Are these typical issues? Are they generally user error? Is it possible to fill out a form, hit submit, and have the system fail but no error reported?