Doesen't send mail with mail()

Hello there! Yesterday i just realised this problem - server can't send mail with php function mail(). Basicly what happens - i fill all the infromation, and press send - page starts to loading and loading and loading and so ont - never stops. Problem is not in the code, because PHPBB board can't send any mail too.
But about week or two ago all was ok.

Where is the problem?

OS: Ubuntu-Server 7.10
Installed by this tutorial.

 

Are there any errors in your mail log or in Apache's error log?

 

Thanks for reply! Problem solved by it self - all works now.

 

What did you do to fix it?
I'm running cubepanel and have the same problem.

thanks for answering

 

I writed already - it solved by it self - just restarted the server.