TOPIC: Problem sh404sef, Joomla 1.5 & DT Register 2.2.4

Our site worked fine up until I added sh404sef for Joomla 1.5 on our site with DT Register 2.2.4

I had to add a custom link for the DT Register and also the events I have listed. Once I did this,
I get a Duplicated Email message any time someone registers for an event. I turned off sh404
and it doesnt do this any more.

I also turned off the duplicated email prevention in DT Register and this still doesnt help. It
seems like a conflict with sh404sef...

anyone experience this or have a quick fix?