cannot log in

when going to my log in page -> http://www.infinityloopmusic.com/08/wp-login.php

I get an error ->

Warning: Cannot modify header information – headers already sent by (output started at /home3/infinity/public_html/08/wp-content/themes/Transmission-final/wp-transmission-04/functions.php:18) in /home3/infinity/public_html/08/wp-login.php on line 260

Warning: Cannot modify header information – headers already sent by (output started at /home3/infinity/public_html/08/wp-content/themes/Transmission-final/wp-transmission-04/functions.php:18) in /home3/infinity/public_html/08/wp-login.php on line 272
Infinity Loop Music

Then when I try to log in with the correct username: admin + password…
I get this error message->

Warning: Cannot modify header information – headers already sent by (output started at /home3/infinity/public_html/08/wp-content/themes/Transmission-final/wp-transmission-04/functions.php:18) in /home3/infinity/public_html/08/wp-login.php on line 260

Warning: Cannot modify header information – headers already sent by (output started at /home3/infinity/public_html/08/wp-content/themes/Transmission-final/wp-transmission-04/functions.php:18) in /home3/infinity/public_html/08/wp-login.php on line 272

Warning: Cannot modify header information – headers already sent by (output started at /home3/infinity/public_html/08/wp-content/themes/Transmission-final/wp-transmission-04/functions.php:18) in /home3/infinity/public_html/08/wp-includes/pluggable.php on line 595

Warning: Cannot modify header information – headers already sent by (output started at /home3/infinity/public_html/08/wp-content/themes/Transmission-final/wp-transmission-04/functions.php:18) in /home3/infinity/public_html/08/wp-includes/pluggable.php on line 596

Warning: Cannot modify header information – headers already sent by (output started at /home3/infinity/public_html/08/wp-content/themes/Transmission-final/wp-transmission-04/functions.php:18) in /home3/infinity/public_html/08/wp-includes/pluggable.php on line 597

Warning: Cannot modify header information – headers already sent by (output started at /home3/infinity/public_html/08/wp-content/themes/Transmission-final/wp-transmission-04/functions.php:18) in /home3/infinity/public_html/08/wp-includes/pluggable.php on line 770

I think my new template is causing the issue here -> http://www.themelab.com/2008/03/22/transmission-free-wordpress-theme-33/
how can i resolve it though? any ideas?

If not…
I’m wondering how to reset back to my default theme because I believe it is this one that might be causing the problem.

any help would be much appreciated