No data received problem

I installed Yii as instructed (and also used requirements/index.php for checking health of installation, everythings was ok), then created helloworld by using yiic tool. When I entered the localhost/helloworld/index.php in browser, it was redirect to www.localhost.com/helloworld/index.php. After some search, I realized that it caused by Firefox not being able to get a good connection with the local server and then trying to "fix" the address. By disabling this feature (Type about:config in the address bar, Find browser.fixup.alternate.enabled. change it to “false”) I got ride of this annoying behavior but still I have the problem: The connection was reset.

I tried wget localhost/helloworld/index.php and got following response:

Resolving localhost (localhost)… 127.0.0.1

Connecting to localhost (localhost)|127.0.0.1|:80… connected.

HTTP request sent, awaiting response… No data received.

Retrying.

By using echo-die() mechanism I found the problem raised somewhere in running widget. I think it should be some configuration problem, but I cannot find anything useful. any good suggestions?