session-start() error

[smiteme]

i get this error when i use the sesion-start function.

<b>Warning</b>:  session_start() [<a href='function.session-start'>function.session-start</a>]: Cannot send session cookie - headers already sent by (output started at /home/smiteme/public_html/login.php:76) in <b>/home/smiteme/public_html/login.php</b> on line <b>77</b><br />
<br />
<b>Warning</b>:  session_start() [<a href='function.session-start'>function.session-start</a>]: Cannot send session cache limiter - headers already sent (output started at /home/smiteme/public_html/login.php:76) in <b>/home/smiteme/public_html/login.php</b> on line <b>77</b><br />

the call to the function is before any html, and the same code works fine on my localhost.
any ides?