Error while posting

Hi we have a site which is shifted from php 4 to php 5. The problem that arisen is we have a form class which automatically inserts data in database depending on the form elements. so if we create 5 form elements then the class automatically inserts in those field names. Now on php 5 when we post a form many unwanted values are posted and the form class insert failes. for eg filepath, _filetype, _dbfield, _dbvalue, _imagewidth, _imageheight, _thumbwidth, _thumbheight are posted and the form class try inserting this data into db with the respective names which actually doesnt exist. Can something be done on php ini file on php 5 this extra vaues are not posted. On php 4 the same code works perfect... Regards, Prashanth