The address may be changing on you.
This is the address for the pdf file you can use on your computer.
http://manuals.info.apple.com/en/iphoneuserguide.pdf
This is iPhone interface guide. Use your iPhone safari
and type the address in and when you select Go make
sure the address doesn't change to pdf.
http://help.apple.com/iphone/4/interface/
If it tries to change to pdf stop it and re-type
the correct address. Post back and let us know.
A