form reload with php as cgi ?

Hi, I am trying to use a php/mysql based project system (achievo.org), but when I enter data via the forms, I get a reply "entry has to be unique" even though it has been written to the db. Someone said it might be because I have php as cgi rather than a isapi module and therefore the form reloads itself - leading to a db-error. Can anybody clearify that and perhaps how to do a work-around since my host has php as cgi and does not want to change? Gorm