its most likely a cookie issue then.
please dont take this as a condescension but when you say it "cannot display the page" what error type is it?
is it a 404, 500, these are things as a web dev you have to know, and have to remit to groups when posting a problem.
"After a bit of time i try to update the files "
Im going to assume you mean you are making on the fly updates to scripts, and testing on localhost, right?
If so, do they involve sessions/cookies at all?