PHP contact form help?

I have uploaded a test of the PHP contact form, everything works fine on one of my hosts that i tested, then i tried to test the PHP on another host and for whatever reason when the form gets filled out and you press the submit button, a download box appears, asking if i would like to download the page and the mail doesnt get directed to my inbox…

Why would this download window appear? and how would i get rid of it and let the form submit to my inbox? Is this a problem i should contact the host about or is there away of coding this to fix it???

If anyone could help that would be great…
Cheers
Peter.D